I would follow AdrianH advice. The Malware resident experts that lurk around the Avast forum do a excellent job, better than most retail aka geek squad at cleaning up malware and you probably won’t need to reformat or anything of the sort.

I only advice I would personally give is after your are done cleaning your system, to change the password on any sensitive accounts like banking, social, email b/c it is fairly common for malware to try to steal the passwords from these type of sites.