Trying to connect again to WiFI with 8520

I have an 8520 BB AT&T with out a data plan. I have had the BB now for about a month. I was able to connect to my home WiFi and the WiFi of other places great (McD's and etc)--but with in the past week I could NOT connect to any WiFi network I was once able to do so. When I search for the networks they show that they are there--but I can't access any internet sites.

I have tried to look at other posts--but none of them seem to speak to me. I would greatly appreciate any help anyone can provide. Thanks!!!