cannot save files windows 10

I was able to re-install Libre by not creating the short cut. Now I have a similar problem that looks lot several users are having. I can not save any files after I make some updates - ‘File not found’ 'Check the file name and try again. I also created an empty spreadsheet and copied the data into the new spreadsheet- that did not work. Could lose a lot of data, need some help to resolve this.
Thanks,
Bob Grabowski

You have already been given the answer about Windows Defender here, and you had ignored it.