That's the problem with disconnects. You should be easily able to retrieve a slightly older version of your character, though.

First things first:
Start doing periodic backups of your personal data. As you've seen, computers and software can crash and burn, reducing your precious personal data to cinders.

NOT doing personal backups is a recipe for disaster. External hard drives are cheap, your personal data is priceless.

Now onto the real thing.

There's two locations on your computer to search for your Valheim save games:
1.
2.
...where YOURSTEAMID is a string of eight numbers resembling your Steam ID.

1.
2.

If you had Steam Cloud turned OFF (HIGHLY recommended as it is mostly responsible for these world resets), you can find your worlds and its older copies at the location indicated in location #1 inside the folder "worlds_local". Your character(s) will reside in the "characters_local" folder.

If you had Steam Cloud still turned ON, these files will be at the location indicated in #2 inside the folder "worlds". Your character(s) will reside in the "characters" folder. IF you turned Steam Cloud off AFTER the reset happened, your older world/character copies will still be at location #2!

Just make sure to check BOTH locations to not miss your characters and worlds.

In the extreme case you can't seem to find your character or world in either location you can check the Steam Cloud for your saves:
https://store.steampowered.com/account/remotestorageapp/?appid=892970

For the next steps to work, we need to make sure that we can actually see all extensions. If you already have this turned on, you can directly move to step 3. "Restoring your world".

1. Open a file explorer window by clicking on the yellow folder icon with the blue bracket beneath it shown in the taskbar at the bottom of the screen.
2. Open the "File" menu in that window.
3. Select "Change folder and search options". Window "Folder Options" will open.
4. In the "Folder Options" window, select the "View" tab.
5. In the list of options UNCHECK "Hide extensions for known file types". You may have to scroll down to see it.
6. Click OK to accept the change and close the window.

You can leave the file explorer window open or close it.

The older copies of your character files should have a name like:

YOURCHAR should be the name of your actual character.
The long string of numbers is the date and (I guess) a serial timestamp when the world was saved. In the example above Aug, 17th, 2022, at some later time.

So what you need to do now is:
4. Create a COPY of both folders listed at loc. #1 and #2 and put them somewhere save, preferably on an external drive.
5.a. If you have been using Steam Cloud before your little "accident", you need to check inside the "characters" folder at location #2.
5.b. If you have NOT been using Steam Cloud, you need to check inside the "characters_local" folder at location #1.
6. No matter where you are now, you should find older copies of your world files as indicated above.
7. Make a COPY of the most recent backup .fch file (check your modified date) and put it on your desktop.
8. Rename the file, so it just resembles "YOURCHAR.fch". Again, YOURCHAR is your actual character name.
9. Move this file into the folder you originally grabbed it from.
10. Go back into Steam.
11. If you've been using Steam Cloud, you will most likely encounter a Steam Cloud conflict. DO NOT resolve it by clicking on the icon. DO NOT DO IT!
12. Get into the game and check if your character is back in order.
13. It is now HIGHLY recommended to MOVE both your character and world to LOCAL using the buttons in the main menu from Valheim.
14. Once that is done, it is HIGHLY recommended to TURN OFF Steam Cloud in the global Steam settings.

Let me know if that helped, or if you need more detailed instructions.