Need help with a Price Pfister shower faucet.

Hi all. I hope you can help me with a problem I've had for a while in my bathroom shower. A few years ago I was having a problem with hot water coming out the cold water taps. It turned out the problem was a bathroom sink faucet, but the maintenance man our complex sent out didn't figure that out. His solution to the problem was to reef on the faucet so hard it broke. He reached inside with a screwdriver and shut off the flow so he could replace the valve. Problem is two-fold now. First, he no longer works here so I can't ask him what he did. Second, I have no idea what part I'm looking at.

Can you help me find out what the part and model number is in case it needs totally replacing, and can you tell me where the flow shut-off is so I can re-open them.

There are two gate valves before the shower valve, but I don't see how he could have accessed them to shut them off.

I have taken some pictures to help you identify the part.

The black hose is the drain from the A/C.
Thank you for your help.

The Price Pfister cartridge you need is their 900-022. There is no fixing it, if it fails you swap it out. I can't see any stops in your picture, so I can't help you there.