Garry's mod won't stop validating

[Mafia_Beagle55]

this is not for me, this is for my friend. He uninstalled the game and left his computer for a couple of minutes, when he came back he saw that he had been kicked out and the game was validating. He started waiting and several hours later it had not finished, he left it on all night and it was still not done the next day. if anybody knows how to fix this please tell us. i will leave his discussion in the comments.

[Mafia_Beagle55]

https://steamcommunity.com/app/4000/discussions/1/2520275467400307866/