you have to restore your backup. you need to put the user folder back from your previous windows, or at least the irongate folder part of it under appdata locallow.

Awe that's rough! Is this a local game or a server? If server then ask the admin to locate your old home if local then open the console and use Devcomands to reveal the map and fly to there.

If you made a cartography table then you can restore just what you had mapped to it again later. Again in Dev mode hide the whole map then restore from the table.

There are probably newer and better guides to the Dev command route but read this over if you need to
https://www.pcgamer.com/uk/valheim-cheats-console-commands/

I guess your memory. Or do you have mates on this map?