Originally posted by Wumbo:

i couldnt even launch my game. I uninstalled all mods and it worked after. Make sure you dont have any mod files in your directory still.

Do you mean removing all mods from BepInEx's plugins folder?
If that is how you disable all mods you're doing it wrong because BepInEx would still be running and it is pretty much the mod.

Just rename
This stops BepInEx cold in its tracks because it doesn't even get injected into the valheim.exe process anymore => completely disables BepInEx (and all mods requiring it).