Trying to retreive garrysmod and addons folders

i dont know what happend exactly i was on steam playing gmod then i went off it and tried to download a random file (off i put it on /steam/steamapps/<actname>/garrysmod/garrysmod/addons but then i got an update then it went blank now i only have /steam/steamapps/<actname>/garrysmod/sourcemods i have tried everthing to get them back but some people say it would work if i deleted steam completely meaning losing my games and stuff im willing to do that if it helps.