Need a clip for a strum ruger 22 cal automatic pistol serial no?

What you need is a magazine, and you can find them at gun shops and gun shows, or, if you want to skip all of that, you can order them from a number of websites, including (but not limited to) Ammo Land, J&G Sales, Gun Broker, Auction Arms, Midway USA, Guns America, and from the Ruger website, among others.