[Insert Uncle Zaths Generic Rant on how BAD cloud saves are currently]

So not going over old ground I devoutly hope the OP gets his 129 days of progress back as that suxx.

But for the love of Mike turn that cloud garbage OFF! Its just not in a state (and this may not be Irongates fault either) but the cloud saves a liability in this mans opinion right now do no t use...

restore your backup file if you can find one that is intact. Look in the folder for a recent larger file, the smaller file is probably an indication of the untouched world, but modification date may help too. Zip your entire folder before launching the game again too, in case it destroys what you have left (if anything). Turn the steam cloud off. It is a constant source of these kinds of problems.

keep manual backups of your characters and worlds out of their folder. Stuff happens.

from pinned
Where can I find my save files?
When you start the game for the first time after the Cloud Save Patch from 20th June 2022, your save files will be in the same folder as before, these will be marked as ‘legacy saves’. When you play with a character or world, when it saves the next time, the file will be moved to one of two locations.

By default, if you have Steam Cloud saves enabled in your Steam settings (which is enabled by default), the file will be moved to the new cloud location. It's found in your steam/userdata folder, which is a folder not meant to be manipulated manually, but if you want the files to make manual backups for example, you can find the paths below.

If you have disabled Steam Cloud saving in the past, your saves will instead be moved to a new folder in the same base directory as the old saves, but with the new folder called “worlds_local” and “characters_local”.
Any time a file is moved between folders (either automatically from legacy, or manually using the button, a local backup is created). (See details below ...)

Local files can be found at:
Windows: C:\Users\USERNAME\AppData\LocalLow\IronGate\Valheim
Linux: .config/unity3d/IronGate/Valheim

Steam Cloud save folder:
Windows: Steam\userdata\NUMERICSTEAMID\892970\remote
Linux: .steam/steam/userdata/NUMERICSTEAMID/892970/remote

A final note on the Steam Cloud save folder – In the ‘892970’ folder you will also see a folder named “ac” (auto cloud) which stores your old legacy saves. With this new system, we simply keep this one enabled as well.

What do the “Move to Local” and “Move to Cloud” buttons do?
These buttons will move the selected save file to the local folder if it's currently on the cloud, and it will move it to the cloud if it's currently located locally. AND a backup will be created each time!

Please note that the backup files are not deleted automatically, so pressing it many times may create a lot of backup files which can use up a lot of disk space if your worlds are large.

How do I make manual backups of my save files? (And should I?)
It's always a good idea to make backups of your save files that you've invested a lot of time in for all games! Even though we game developers do our best to keep systems safe, there is always a chance of files being corrupted or sync issues causing loss of data, or your hard drive might crash!
To make a backup, simply locate the save folder (see above) and copy the files to a new location. An even easier way of doing this in game now, is to simply use the new “Move to Local” button twice in a row, which will move the file first to your local drive, and then back to the cloud, and leaving a backup in your local folder!

How do I recover a backup file?
The backups created when files are moved between locations have a “_backup” suffixed to their filename so that they do not show up in game, simply remove this from their name and you can see them in game again.
If you want to restore manual backup files, simply copy the files back into the local save folder, and then you can move them to the cloud again, just make sure you don't overwrite a world you progressed further in!

If we are multiple people using the same PC, how can we play in the same world?
If you want to use multiple Steam accounts to play in the same world at different times on the same PC, you will need to move the world to a “local save” as the new cloud location is bound to your account to prevent data loss.

Why do some files show their names and something else in parentheses now?
Since save filenames can now be renamed, if the original world name and the file name differ, this will show in the parentheses.

How do I know if my saves are on the cloud or local?
There is a text and icon under each character telling you where the save is located, and the same icon next to each world showing where it's located.



and

this link should point to your cloud files https://store.steampowered.com/account/remotestorage

good luck