System restore sometimes works, but sometimes is the cause of "recurring infection." Many kinds of malware insert a line in the registry to reinstall themselves every time you reboot, if the malware itself has been removed. If you've rebooted a half dozen times, ALL restore points may be thus infected.
The ONLY solution where this happens is to turn off "Restore," which deletes all records of past system configurations, remove the malware, and turn "Restore" back on only after the malware has been successfully removed.
Once the system is "clean," and System Restore is turned back on, a new restore point will be created and stored the next time you reboot.
IFF this is necessary, the instructions for removal of the particular infection you have, from any of the reputable AV makers, should tell you do do it.
Nearly all major AV makers have "remote scan" utilties you can use (no charge) to determine whether an infection is present. You might have to "purchase" one of their advanced products to have them remove it, but they will tell you what's there, and generally will direct you to "manual removal methods" that you can use without buying anything.
Most AV makers recommend a scan using their remote scan utility before installing/reinstalling their AV software so you don't have to own their stuff or have it on your computer to get their free scans.
Any of the popup "free removers" is as likely to be a source of new malware as to be a help.
Go ONLY to known reputable AV makers for advice, print their instructions if necessary, and follow them carefully.