You will need a WPA or WEP key to connect unless the access point has open security. The key is a several character long string that is entered on the client to connect to the access point. If you don’t have the original key and there are no other devices, then create a new key and reset the router with that key and enter it in your client. If there are other clients, you can still create a new key but they will need to have the new key entered to permit them to connect to the wireless router.
I am not sure if you have already solved this problem, however, sometimes it is overlooked that the router and computer must be shutdown, router rebooted first, and then the computer rebooted again. Are you still having trouble connecting to the router?
To view the WEP or WPA connect directly to the router by this machine or another using your network cable. Then access the properties page of your router. You did not mention what router you are using. If it is a linksys go to 192.168.1.1 in your web browser. You will be prompted to log in. If you have not changed the defaults, on older LinkSys routers, the default username is blank and the default password is “admin.” On newer Linksys routers, both the default username and the default password are set to “admin.”. If you have changed these (and it is good security practice to do so obviously) type in the new ones. If you have forgotten them you have to reset the router to factory defaults. If this is not a linksys router then you will need to get the settings for the router you are using.
To check your wireless card drivers go into the device manager and see if there is a bang (exclamation point) or a question mark on the wireless device there. Install or update the driver if there is.