Copied from internet link
due to changes not sure if file locations are the same but you want to look for the .old thing.


How to Back Up Valheim Save Data

To back up your Valheim save data, navigate to the game’s files. You can find them here: C:\Users\Username\AppData\LocalLow\IronGate\Valheim\. In the event that your AppData files are hidden, you can manually pull them up by typing %appdata% into the Windows search bar.

Folders for characters, and worlds can be found there. Create a copy of these folders and place them somewhere easily accessible, such as the Desktop.

Follow the same filepath and seek out the .db.old and .fwl.old files. The “old” portion designates previous versions of worlds and characters that have been saved. Deleting the “old” from the file name can restore those points.