Plumbing Questions? Ask a Plumber and Get Answers ASAP.
Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can continue our conversation.
You'll have to rebuild the shower valve. It looks like a Delta so most parts are pretty commonly available. You have to turn the water off to the house then remove the handle and the bonnet behind the handle so you can remove the cartridge. Many Delta valves have neoprene seats which you can get at the big box stores. You won't know just what you need until you get it apart.
Your only other viable option would be a plumbing supply house maybe a good hardware store. There seldom are shut offs to just the shower but some valve have built in shut offs. You can find this out by removing just the handle and the round trim plate at the wall. If your valve has shut offs you see 2 stems with screwdriver slots where the water pipes connect to the valve inside the wall. Just turn the screwdriver slots all the way clockwise to shut it off.
Show me a pic of the screws in the handle
That's not what I meant. If you can't get the handle off I need a pic of the handle showing me the problem screw. That screw looks like one that holds on the trim plate at the wall not the handle
You already have the handle off. You need to remove the other screw in the round plate at the wall so you can pull the plate off
It should come out easily. Can you give me a pic straight on of the screw and the center of the valve. I'm wondering if the bonnet in the middle is in the way. Shouldn't be
There's nothing that should stop it from coming out. Maybe it's seized up but in 40 years that's never happened to me. This won't stop you from fixing this but it will stop you from just shutting off just the shower.
You have to remove the cartridge in the valve (the white piece with the stem coming out of it in the middle of the valve). Judging from what I can see you've got maybe a 50/50 chance at best of finding the parts at Home Depot. The downside and it's a big one is if you damage something taking this apart you risk have no water at all in the house until the plumber gets there to replace the entire valve. My suggestion is to leave it alone and tackle this next week when you won't have to pay extra if you need a plumber.