Step one, I’d suggest backing up your corrupted vault as well, before trying to fix it. That way, if anything goes wrong while fixing, you can roll back and try again.
And then inside your vault, there should be a hidden .obsidian folder. Depends on your OS how to show hidden files. But if you delete that and replace it with the one from your backup, it should restore your plugins, themes, and your workspace layout. You may have to reinstall any plugins you installed after the backup was taken.

If that doesn’t work, there may be a chance some of the files in your Obsidian app folder got corrupted. I personally have no idea what may go wrong if that happens. But I don’t believe the contents of your vault will really be affected by that folder. So if you had to, reinstalling Obsidian might fix that.
Again depends on your OS. In Mac it’s ~/Library/Application Support/obsidian