Copy your appdata>roaming>KODI directory to your desktop. Then uninstall KODI and resinstall it to see if you have a working system. Since it's a fresh install, it should work fine. Then you can copy the directories from your desktop back into your appdata>roaming>KODI>addons to have the addons again. You would also copy the folders from your desktop (appdata>userdata) to appdata>roaming>KODI>userdata>addondata to retain your user settings and favourites, etc.
You could just copy the whole thing from the desktop to your appdata>roaming>kodi and overwrite the files, but you might wind up with a non-working system again. I guess it would depend on what is mucking up your system at present.
Can't really hurt to try, since you have an unworking system at present.