I can't log in to my yahoo account - Yahoo YHT-630 System

If you ever find yourself with a locked Yahoo account, it's likely due to multiple incorrect password attempts.

As a security measure, Yahoo's email and chat client servers automatically lock your account to prevent unauthorized access after there have been multiple invalid password entries.

The ID Lock security measure safeguards a Yahoo account from unauthorized users who try to access your account without permission.Cause

After multiple incorrect password entries to a Yahoo account, the server automatically sets a lock on it.
This happens because every time a Yahoo Account holder logs into his account, he's logged in with a cookie.

A cookie is an information packet that proves you are the valid account holder.
However, when a person tries to access an account with many failed attempts, the cookies expires, triggering the ID lock on the account.
24-Hour Wait

A Yahoo account holder must wait up to 24 hours before accessing the account again.
The lock on the account expires within 24 hours from the time the account was locked.

Unlock Using Another Server Since Yahoo! has many servers around the world, a user can log into his account by visiting a different Yahoo server address. (See Below.)
http://thingsaboutcomputer.blogspot.com/2009/03/how-to-unlock-yahoo-when-account-is.html

Copy and paste a Yahoo! server URL into the address bar of your Internet browser to access the website.
Enter the Yahoo! ID and password in their respective fields, and click on "Log in" to access your yahoo account.
Avoid Yahoo Account Locks
To prevent future Yahoo! account locks, a user should limit the number of times he tries to enter a password.

If an account holder has forgotten his password, he should use the "Forgot Passsword" feature to reset the password.
http://help.yahoo.com/l/ca/yahoo/edit/id_password/edit-22.html

I CANT LOGIN TO MY ACCOUNT,WHAT SHOULD I DO TO GET MY OLD EMAIL ADDRESS?

You don't have to create the account in Yahoo Messenger. If you have a Yahoo Mail account use that one to log in. If you don't have one, you can go to http://mail.yahoo.com/ click on Create New Account and follow the prompts. Once created use that account to log in on Yahoo Messenger.

You can't. You cannot be simultaneously logged into 2 yahoo accounts. You need to log out of the existing one to log into the second yahoo ID. However you may be simultaneously logged into 1 yahoo email and ine google or hotmail. The way around this is to have a second user account on the computer and be logged simultneously into both user accounts, and be logged into a diffferent yahoo email in each user account

1. Click on the Yahoo! Messenger icon found on your computer desktop, or enter the program from the Yahoo! home page. Log in to Yahoo! Messenger with your user ID and current password. Click the "Yahoo! Messenger" link when the Yahoo! Messenger window opens.
   
2. Go to "My Account Info." This will take you to the Yahoo! Messenger account information page.
   
3. Find the link that reads "Change Password." Type your old password into the first field, then type a different password into the new password field.
   
4. Enter your new Yahoo! Messenger password into the next form field to confirm it. Save the new password into your Yahoo! Messenger account.
   
5. Log out of Yahoo! Messenger, then log in again. Test your account by entering your user ID and new password.
   

This is because someone else or some other thing is logging into your account elsewhere thus logging you out. Could you have an iPhone, phone, another computer (i.e. Laptop) with your account saved. i.e. if you startup your laptop or someone else does at your house/office and it automatically logs your pre-saved Yahoo account in while your already logged in, it will log you out and return to you that message.

To unlock your account

1) Close Yahoo Messenger completely
2) Go to Yahoo WEB Messenger
3) Log in there
4) Hey presto your account is unlocked
5) log out of web messenger
6) reboot computer
7) Yahoo Messenger should now log in properly

If this has helped you then please help me and vote kindly, thank you.

you cannot sign into more than one yahoo/ gmail /etc simultaneously... you have to sign out from one to log-in into another account. But you can use different browser to log in to various account. I mean, use internet exploer to log-in into your first account. then use firefox /opera/any other browser to log into ur second account.

I believe you have chosen 1 type of account and now because you have done it yourmail plus account is not available you will have to go to yahoo site and search for an answer
I have found that if a program works the way you want do NOT upgrade it as problems can occur and files lost

have you tried lost password recovery? also someone may have accessed your account and changed your password. might want to do a lost password request and see if it helps any.