Internet Connection

I cannot connect to the internet on my year old pc. Two reps from AT&T have come to my home to help, but could not figure out the problem. The first rep could not figure it out. The second rep said it was a problem with the expired norton antivirus. He said there was a firewall problem, because I did not renew. He deleted the software, but it did not solve the problem. I've only had the pc for a year. I only use it to shop, pay bills and games. I've used no memory and I'm totally green when it comes to computers. I really need help immediately. Has anyone else experienced the problem? I'm desperate and
tired of going to the public library to use the computer.