How to sign in as another user + Yahoo

As per the policy mentioned by Yahoo, if a user enters a wrong password too many times, his account gets locked for 12 hours. If you are not able to access your account even after 12 hours, you can refer to the following Yahoo support page:
https://my.help.yahoo.com/kb/yahoo-account/learn-sign-sln2051.html

Hope this will help you.

GuruAid.com

If it says user name hasn't been taken then you haven't done it properly. Make sure you're using the username you signed up with.
If it's not working then sign up again because you shouldn't need to enter an activation code to open the account, only to recover it.

If you suspect that someone has hacked your Yahoo! account or if you attempt to log in your account too many times with an incorrect password, Yahoo! might lock you out of your account.
After several failed login attempts, the Yahoo! security feature locks your account for a predetermined amount of time to prevent unauthorized users from accessing your account.
Unauthorized users might use your account to send unsolicited emails or intrude on your private content and emails.
Although being locked out of your Yahoo! account can be frustrating, you can gain access to your account and change your password after the lock expires.

Wait 24 hours.
Return to the Yahoo! website and click the "Sign In" link at the top of the page.

Click "I Can't Access My Account."
Select "I Forgot My Password" or "My Password Doesn't Work" from the list of options.
Click the "Next" button to proceed.
Enter your Yahoo! ID in the "My Yahoo! ID is" field.
Enter the security code in the "Enter the Code Shown" field.
Click the "Next" button.

Click "I Cannot Access Any of the Above" and click the "Next" button.
Type the answers to the security questions in the appropriate fields.
You set these security quests when you created your Yahoo! Account.
Click "Next."
Enter a new password in the field and verify the password by retyping it in the field.
Click the "Next" button and Yahoo! resets your password.
The new password is effective immediately, allowing you to sign in your Yahoo! account.

Many times, you can recover a hacked or compromised Yahoo! account after using on-site password-recovery tools.
The process can take a few minutes to complete, but once you are finished you'll be back in your account.
If the password-recovery method does not work, then you can always contact the security group at Yahoo! Inc. via email.
Of course, you'll need access to a secondary email address to message the company's support team.

Type "login.yahoo.com" into the browser's URL address field.
You are greeted by the Yahoo! account sign in page.
Click the "I can't access my account" link in the box on the right side.
Select the "My account may have been compromised" option from the choice of sign in problems.
Click the "Next" button.
Type your Yahoo! ID and security code on the next page.
Click "Next" to continue.
Select an alternative email address to send a reset link to.
This only works if you previously added a secondary email address.
If not or the alternative email address has been tampered with, then select the "I can't access any of the above" option.
Click "Next."
Answer the security questions on the next few pages.
You will usually have to answer at least two security questions.
Enter a new password and repeat the password when prompted.
Click the "Next" button to finalize the password-reset process.
Recover a compromised Yahoo! e-mail account
http://www.trishtech.com/internet/recover_a_compromised_yahoo_account.php
How to recover your Hacked Yahoo! Account
http://pctechnotes.com/how-to-recover-your-hacked-yahoo-account/

Yahoo Messenger Has Been Locked

As its name implies, Yahoo Messenger allows you to exchange instant messages with other Yahoo users.
But the software's capabilities extend far beyond one-on-one text conversations.
You can use Yahoo Messenger to participate in chat rooms, share photos, make telephone calls, video chat, play games and more.
When you experience problems accessing your Yahoo Messenger account, you may receive a message that it has been locked. Locked Accounts Yahoo places locks on Messenger accounts as a security precaution.
The locks take effect when there are multiple, failed attempts to access a user's Yahoo account.
Even if you unsuccessfully tried to to sign in to a different Yahoo product, you may find your Messenger account locked.
Unlocking Accounts
To unlock your account, go to Yahoo's sign-in page and enter your user ID and password.
When you reach your My Yahoo page, click on one of the Quicklinks you see on the left side of the page.
Leave your My Yahoo page open.
Sign into Yahoo Messenger for the Web, then try to sign into Yahoo Messenger.
If you are unsuccessful, contact customer care.
Current Versions
"Account locked" messages aren't the only sign-in problems you may experience with Yahoo Messenger.
Some users experience sign-in issues when using older versions of the software.
Yahoo engineers recommend upgrading to the newest version of Messenger.
To determine what version you have, look for the "About Yahoo Messenger" link under the Help menu.
Visit the Yahoo Messenger website to determine if this is the current version.

Other Sign-in Issues
When you have trouble signing in to Messenger, verify that your Internet connection is working. You can do this by navigating to a webpage.
If you are able to sign into Yahoo Mail but not Messenger, there may be a problem with your connection settings.
The Yahoo Help website offers troubleshooting steps for these settings.

Which email account there are many ?

It is not uncommon for users to forget their user names and passwords, especially when trying to access an email account not often used.
Email providers like Yahoo! and Google are aware that users forget and have implemented a way to identify the user in this situation. In order to use this retrieval method, you must have submitted an alternate email address when you signed up for that email.

Go to the email sign-in page.
Notice the option underneath the login fields for users that have trouble signing in; in Yahoo! Mail this option is "I forgot my Yahoo! ID" and in Google Gmail this option is "Can't Access Your Account."
Click this option.
Enter the alternate email address entered when you set up up your email address.
Yahoo! Mail users also need to enter the birth date, country and postal code entered when the email address was set up. Click "Next."

Log in to your alternative email address and click the email provided.
Your email user name is available in the body of the email.
Click the link within that email to reset your email password.
To reset your email password, the provider might require that you answer your security question.
Go back to the email sign-in page and log in using your user name and new password.
http://help.yahoo.com/l/us/yahoo/mail/yahoomail/account/account-10.html
Hotmail have a forgotten password link but you must have another email adress to send your forgotten password to
just open up another email acc at hotmail/live.com eg: [email protected]
in the right hand corner on the hotmail homepage you should see help center
down in the bottom right hand corner tab click on that another page will open you should see another help center click on that again another page will open with account calender contacts essentials
click on the account tab another page will open with if you have forgotten your password or are having trouble signing in yet another page will open get help with your password problem
or signing in click on it you should see something like I forgot my password or I know my password but am having trouble signing in I think someone else is using my hotmail account
at the sign in for your hotmail account click on forgot password tab another page will open then on the reset password tab

Now which email account is it ?.
hotmail , yahoo , msn , outlook , live mail ,gmail ?.
It is not uncommon for users to forget their user names and passwords, especially when trying to access an email account not often used.
Email providers like Yahoo! and Google are aware that users forget and have implemented a way to identify the user in this situation. In order to use this retrieval method, you must have submitted an alternate email address when you signed up for that email.

Go to the email sign-in page.
Notice the option underneath the login fields for users that have trouble signing in; in Yahoo! Mail this option is "I forgot my Yahoo! ID" and in Google Gmail this option is "Can't Access Your Account."
Click this option.
Enter the alternate email address entered when you set up up your email address.
Yahoo! Mail users also need to enter the birth date, country and postal code entered when the email address was set up. Click "Next."


Log in to your alternative email address and click the email provided.
Your email user name is available in the body of the email.
Click the link within that email to reset your email password.
To reset your email password, the provider might require that you answer your security question.

Go back to the email sign-in page and log in using your user name and new password.
http://help.yahoo.com/l/us/yahoo/mail/yahoomail/account/account-10.html

As its name implies, Yahoo Messenger allows you to exchange instant messages with other Yahoo users. But the software's capabilities extend far beyond one-on-one text conversations. You can use Yahoo Messenger to participate in chat rooms, share photos, make telephone calls, video chat, play games and more. When you experience problems accessing your Yahoo Messenger account, you may receive a message that it has been locked.


Locked Accounts
Yahoo places locks on Messenger accounts as a security precaution. The locks take effect when there are multiple, failed attempts to access a user's Yahoo account. Even if you unsuccessfully tried to to sign in to a different Yahoo product, you may find your Messenger account locked. b> Unlocking Accounts b> To unlock your account, go to Yahoo's sign-in page and enter your user ID and password. When you reach your My Yahoo page, click on one of the Quicklinks you see on the left side of the page. Leave your My Yahoo page open. Sign into Yahoo Messenger for the Web, then try to sign into Yahoo Messenger. If you are unsuccessful, contact customer care. b> Current Versions b> "Account locked" messages aren't the only sign-in problems you may experience with Yahoo Messenger. Some users experience sign-in issues when using older versions of the software. Yahoo engineers recommend upgrading to the newest version of Messenger. To determine what version you have, look for the "About Yahoo Messenger" link under the Help menu. Visit the Yahoo Messenger website to determine if this is the current version. b> Other Sign-in Issues b> When you have trouble signing in to Messenger, verify that your Internet connection is working. You can do this by navigating to a webpage. If you are able to sign into Yahoo Mail but not Messenger, there may be a problem with your connection settings. The Yahoo Help website offers troubleshooting steps for these settings. Hope this helps

I can't login on my yahoo to email