Not much to go on.

Okay, if you are using xp, run a boot time scan.

Disable system restore first.

To schedule a boot time scan

right click the “a” ball, click start avast antivirus
click menu, select schedule boot time scan
select the path ie the drive you want to scan.

Make sure system restore is off. Restart your computor.

edited to add

move anything found to the chest, rather than delete!