"could not load library client"

My friend is having an error with his Garry’s Mod. Whenever he opens the game, he recieves a “could not load library client” error.

He’s tried the most common ways of fixing it- deleting his bins, deleting everything in the garrysmod folders, re-installing garry’s mod, renaming the garrysmod folder, pretty much everything that comes up when you search for the error.

Assistance, please?