Loss of wi fi?

After two days of use, my emachines 350 lost its wi fi. All other laptops, phones in the house etc are connected & the computer can see other wi fi networks in the street! Os is Windows 7 starter, and my router is a Belkin.It just wont find my connection. Emachines helpline say its a software problem. I did a system restore + factory reset and also removed the pre installed 60 day trial of Norton. Help!!