Help with recovering files?

So I was in the process of trying to transfer my Forza 4 file to another Xbox via a thumb drive, but it wouldn’t allow it to go through. Me being dumb also ended up with me deleting the profile attached to the account, but not the files themselves. This profile has never been online or tied to any email. I was able to retrieve the files so I have them backed up on my PC, but every time I try to attach them to a profile to play, I get some variation of “your account has been tampered with, you cannot proceed” is there anything big can do about this? I just want my cars back :joy: