proxy server problems

I have my son's 15(N5050) at my home because it has an issue with the proxy server settings and as such i am unable to get on the internet.

I am using an ATT u-verse wireless port and put in the ssid numbers as i was told to and everything was going on just fine and i shut down the system to go out one day and when i returned home and turned the laptop on to go on the web i get a message similer to cain't connect to the internet and that i need to check my proxy server.

I ran all the automated things i could find on the machine and nothing would straighten it up.

Can somebody pleas say they can help me?