Unable to save files in Word, Excel, etc. after possible malware or virus

On 9/18 I did a search in Edge, and suddenly I was flooded with constant popup notifications telling me "virus detected", "unathorized access detected", urging me to click to download McAffe, or Norton, or Windows Antivirus apps. I know these were not genuine but despite running Defender several times, I could not get these popups to stop. Also, I made sure all my MS Defender settings were up to date, Windows up to date, and Defender keeps showing "no issues detected." After 4 hrs.. of frustration, I disconnected from my home network, shut down PC. On 9/19, I reconnected, and popup notifications began again. Once again, tried updating all Security, Malware, Virus definitions, ran another FULL offline MS Defender Scan, & RESTART. This time, popups were gone. BUT Defender shows no record of identifying or removing whatever this malware or virus was?? I hoped all issues were resolved. Then I try saving some work in Word, and keep getting error notice that shows full directory file name of file I want to save, with "file not found". Tried saving various locations, various files, same issue. Tried a quick edit and save of an excel .xlsx file. Keep getting popup error message "document not saved." PLEASE ADVISE??