I need some help of Avast4.8home

Frist,thank you can read this question.I come from China ,My English is not good enough.
I have been use Avast 30days. Iuse it to check my computer yesterday evening. When it tell me find a virus .Because of computer game,I haven’t seen it clearly and remove the file. But today morning ,I find this file is one of important files in my computer. I don’t have any backup about it. So ,I wan’t someone can help me recovery this file. Thank you very much.

what OS do you have xp / vista / win7 ?
what is the virus name ?
where is the virus found ?

Frist,thank you can help me with this question.
My OS is xp.
The virus name is Win32:Malware-gen
This virus was be found in hard-G.In a important file.Do you have any way to recovery the file which I remove by mistake? Thank you.

This will also recover the virus…

PC Inspector File Recovery 4.0 http://filehippo.com/download_file_recovery/

Recuva 1.34.460 http://filehippo.com/download_recuva/

Thanks for your help.