Bought a used zune 1091 everything works but when i tried to use the wi fi it asked for password is there a way to change the old password without knowing it

depends. If you are referring to the admin function of the router then the password to it is only needed to change the router settings.
If you change the Wi-Fi encyrption key on WPA or WEP key via the admin function then any computer using Wi Fi would need to match the WPA key or WEP key to access the wi fi.
If the default password does not work the router may be able to be reset to factory settings if you do not know password which requires you to set everything up again in the router and is not easy to set up unless you know the isp settings and network settings.

Your kindle has a sim card installed for 3G (lifetime licence paid by amazon and paid for on purchase price on the unit) but that is not related to the wi-fi function on your kindle. Your wi-fi service needs to be logged in to with the same password as you use to log any computer on to your router when at home or whatever wi-fi password is required when elsewhere (e.g a bus, train or restaurant).

Well, I may be an 18 yr. old and I may be no wiz but I'm big into computers and there are several solutions to this. 1) If there is a password put in the wi-fi, you need to: have a device in which will be able to put in the type of security and/or put in the EXACT password. 2) Make sure it is YOUR wi-fi you're trying to connect to. And 3) If 1 and 2 don't work, contact the company of which your wi-fi was bought from. I hope this explaination was helpful for your problem.

Turning Wi-Fi on and connecting to a
Wi-Fi network
1 Touch > Apps tab > Settings >
Wi-Fi from the WIRELESS & NETWORKS
2 Set Wi-Fi to ON to turn it on and start
scanning for available Wi-Fi networks.
Tap Wi-Fi menu again to see a list of
active and in-range Wi-Fi networks.
• Secured networks are indicated by a lock
icon.
4 Touch a network to connect to it.
• If the network is open, you are asked to
confirm that you want to connect to that
network by touching Connect.
• If the network is secured, you are
prompted to enter a password or
other credentials. (Ask your network
administrator for details)

Wi-Fi settings determine whether iPhone uses local Wi-Fi networks to connect to the Internet.
Turn Wi-Fi on: Choose Wi-Fi and turn Wi-Fi on.
Join a Wi-Fi network: Choose Wi-Fi, wait a moment as iPhone detects networks in range, then select a network. If necessary, enter a password and tap Join (networks that require a password appear with a lock icon).
Once you join a Wi-Fi network manually, iPhone automatically joins it whenever the network is in range. If more than one previously used network is in range, iPhone joins the one last used. When iPhone is joined to a Wi-Fi network, the Wi-Fi icon in the status bar at the top of the screen shows signal strength. The more bars you see, the stronger the signal. Set iPhone to ask if you want to join a new network: Choose Wi-Fi and turn "Ask to Join Networks" on or off. Join a closed Wi-Fi network: To join a Wi-Fi network that isn't shown in the list of scanned networks, choose Wi-Fi > Other, then enter the network name. If the network requires a password, tap Security, tap the type of security the network uses, and enter the password. You must already know the network name, password, and security type to connect to a closed network. Some Wi-Fi networks may require you to enter or adjust additional settings, such as a client ID or static IP address. You can type it manually by login onto the Belkin's network page using the browser and by copying the static and dynamic IP address.

Wi-Fi Functionality

1. Connects over the last Wi-Fi network you used that's available.
2. If no Wi-Fi networks you've used are available, iPod touch will scan for Wi-Fi networks and show a list of Wi-Fi networks in range. Tap a network and, if necessary, enter the password to join. Networks that require a password show a lock icon () next to them.
3. Option to manually enter your Wi-Fi network name/SSID (if the Wi-Fi network is configured not to broadcast or be displayed to the public). If necessary, enter the password to join.

When iPod touch is connected to a Wi-Fi network, the Wi-Fi icon () in the status bar at the top of the screen shows connection strength. The more bars you see, the stronger the connection.
Wi-Fi Settings

1. Turn Wi-Fi on or off.
   Choose Settings > Wi-Fi and turn Wi-Fi on or off.
2. Set iPod touch to ask if you want to join a new Wi-Fi network.
   When you are trying to access the Internet, by using Safari or YouTube for example, and you are not in range of a Wi-Fi network you have previously used, this option tells iPod touch to look for another network. iPod touch will display a list of all available Wi-Fi networks that you can choose from. Networks that require a password appear with a lock icon ().
   
   If "Ask to Join Networks" is turned off, you must manually join a network to connect to the Internet when a previously used network is unavailable.
   
   Choose Wi-Fi and turn "Ask to Join Networks" on or off. If you turn "Ask to Join Networks" off, you must join new networks manually.
3. Join a Wi-Fi network manually.
   Choose Wi-Fi, wait a moment as iPod touch detects networks in range, then choose a network. If necessary, enter a password and tap Join. Networks that require a password appear with a lock icon.
4. Make iPod touch forget a network, so that the device doesn't join it automatically. Choose Wi-Fi and tap the arrow () next to a network you've joined before. Then tap "Forget this Network."
5. Connect to a closed Wi-Fi network (an available Wi-Fi network that isn't shown in the list of scanned networks).
   Choose Wi-Fi, then tap Other and enter the network name. If the network requires a password, choose Security, tap the type of security the network uses, and enter the password. You must already know the network name, password, and security type to connect to a closed network. Some Wi-Fi networks may require you to enter or adjust additional settings, such as a client ID or static IP address. Ask the network administrator which settings to use.
6. Adjust settings to connect to a Wi-Fi network
   Choose Wi-Fi, then tap the arrow () next to a network.

Reset both password (1) pasword for access router via GUI (2)Wi fi security password WEP or WPA or WAP
For that Connect your router to computer with ethernet cable then you can access it with following default link.
http://192.168.0.1
or
http://192.168.1.1
If you are not able to access it with above ip then check your computers ip address gateway ip is your router ip try with it.
Then it ask for user name and password.
Type user as "admin" and password as "admin" or "password" or blank.
Then you can see configuration page of router.
Then click on administration and change password .
Then Click on wireless settings enable wireless then enable WEP Security then add WEP code .It is your password to connect wi fi.Then save settings and restart router.
Then you can connect your wi fi network with that code.
Let me know if you need further assistance.
Thanks for using FixYa.

For that access your router with
http://192.168.1.1
or http://192.168.0.1
if you cant able access it then reset it
Press RESET button for 10 seconds it is in back sid of router.
then access above link.
type user name "admin' and password as "admin' or blank or "password'
then go to wi fi security first configure your router as WEP then go to wi fi security in advancwed then set WEP key it is your password to connect wi fi .