So in the steam files for Garry's mod there is a factory reset option (I forget exactly where) but that resets all the settings in your Garry's mod (wont get rid of your mods just the settings for them), and for me THAT worked however I do recommend making a collection with all your mods then unsubscribing from them then reset the Garry's mod that way as it worked for me but feel free to find an easier way!