If it is deleted, the game should recreate it. The Mods folder will contain a file named resource.cfg.
If the Mods folder does not exist, it can be created manually. Windows Vista, Windows 7/8, Mac:Users\(Your User Account)\Documents\Electronic Arts\The Sims 4\ Windows XP: Documents and Settings\(Your User Account)\My Documents\Electronic Arts\The Sims 4\ In The Sims 4, there are two custom content folders: Tray for lots and Sims, and Mods for other content.
