What do you mean? Do you keep turning the knobs and the water won't shut off, or do the knobs not turn at all?
Sink ? Shower? We need a bit more info. One problem I have seen with older showers is leaky valves. The older 3 valve rig ( hot cold divert) use a valve gasket on the end of the valve stem. This gasket gets "pressed up" against the valve "seat" to stop the water flow. Over time this gasket get deformed or torn and it will cause a drip or dribble leak. It not repaired in a timely manner the gasket can get so damaged and to fall apart and then damage to the valve seat can occur.
Fortunately this repair is not too tough. You can get a "kit" that has new valve stems, knobs, and seats. This whole kit runs about 50 -60 bucks and is a better deal than buying each part separately.
If your knobs and valve stems are still in good shape you can just replace the gaskets...which only cost a couple bucks.
Thanks for the answers, but I'm still hoping for more ideas.
we need more infor...to provide more answers
Buy a new faucet and replace your stops..... the end.
I agree with Plumber26. There are many affordable faucets that will last years and save you headaches. I like Moen and haven't had one yet that's let me down. Let us know your thoughts.
if you have copper or pex pipes coming out of the wall before your stops you can buy Sharkbite (push-on type) stops that are really easy for DIY
u have built up gunk in ur lines