Because we only lose what we don't backup, no one today keeps their files cut down to one last copy. Format the drive and copy from your backups.
There is likely more to this story like "I don't backup" or the name of the virus or ransomware but without more details, the files are likely gone except for backup copies.
My USB appears to have picked up a virus where the names of the folders have been changed and now can not be recognised when trying to open them. The error message reads "The filename, directory name, or volume label syntax is incorrect" and a folder that what would usually be my name now appears as "thk c" and the USB name itself now appears as "STOSE j O". I don't know what this virus/corruption is or how to fix it. Can anyone help?!