"authenticating" "cd key invalid"

I bought some cd keys off some of the people on this forum today and they were working fine for the first few hours. I accidentally went in to server options when trying to join a server and ever since then when i try to join a server it freezes on authenticating then times out, sometimes it will connect but say invalid cd key, Does anybody know how to remedy this?

I just reinstalled everything and it seems to be working fine