You lost the laptop's wife settings to the router. You need to enter the router and see if it uses WEP or WPA and what the SSID is. Once you have those settings, enter them into the wifi settings on your laptop and you're good to go again.
I have a laptop that I cant get to connect to the internet. My home wireless router (and various neighbours routers) are visible from the laptop but it will only connect with "limited Connectivity" and states the network is "unidentified". When I connect direct to the router with a cable I can connect to the net fine. I have recently restored the laptop to factory settings to try to fix with no success and every forum I have been on hasn't helped so far. I have downloaded the latest network adaptor driver too. I am running Vista and currently have no virus software loaded to get in the way if it helps.
Any help would be much appreciated as I am at the end of My tether!