Virus in my pc?

i have no internet connection. i had avast antivirus in my pc and it was fully updated. i brought this pen drive which had a virus (i did not know then). since then fr 4 days whichever folder i opened, it showed, 'the computer has performean illegal function." but nothing happened.

then i uninstalled avast and installed avira antivirus. it deleted 1078 viruses. but then all the folders that i had opened in the last 4 days had vanished.

they do exist as when i scan the disk, the antivirus scans those folders but still they remain invisible. i tried searching but they did not turn up.

then i installed kaspersky but it failed to do anything

also i cant do 'show hidden folders' as that oftion is also not there. that should be on tools or view but its not there. even my computer literate friend is clueless.

what should i do?? i cant format the pc as it has lots of study material...

advice please...

Virus in my pc?antivirus software

I think you should try AVG Free Editon 8.0 because it detected about 3500 threats on my friend's computer.

Virus in my pc?computer virus

Lets hope its not gone to far.

Do two free online scans these scans remove what they find:

http://www.bitdefender.com/scan8/ie.html