What does Firefox do -- rename it to cookies.sqlite-corrupt or something like that?

Any chance the file is in the Windows 10 "Recycle Bin"? (If you do not have a Recycle Bin icon on your desktop, you can add one through some Windows settings dialog.)

Also, why does your screenshot show the database file in Notepad? If that is what Windows chose to open the file, the file may have an invisible .txt file extension. You need to remove that. To set Windows to show you all file extensions, see:

https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/

(If you were just taking a peek, Notepad cannot show the actual contents of a binary file like the cookies.sqlite database. You need to use a tool that understands SQLite database files.)

It is quite likely judging from the screenshot that the cluster(s) used by the recovered cookies.sqlite have been reused and no longer contain their original content. This can always happen if you use a utility to undelete a file. If such a utility claims that the file has been recovered successfully then this merely means that all clusters are available, but no guarantee that clusters haven't been used and freed again in the meantime.

You can look at a utility to browse System Restore points.

• https://www.shadowexplorer.com/
• https://www.nirsoft.net/utils/shadow_copy_view.html