Faucet stopped working

Recently, I've become the caretaker for my Grandfather's house. There was an issue with the bathroom faucet, the hot water would turn on (Far more then just a drip) when unattended.

Figuring I'd need to replace it, I used the handles beneath to shut off the water (Specifically, to the Hot Water knob.) I assumed, until I had a replacement squared away, I could just turn the water back on underneath when I needed to use it.

Now, the problem: The water, both hot and cold, are almost completely off, and will not turn back on. I have tried turning both knobs beneath the sink as far as they'll take in either direction, it doesn't matter. Other plumbing fixtures, like the shower and toilet are working fine.

I would appreciate any help, I am about as unlearned as one can be when it comes to plumbing.

Sounds like you have to replace those two angle valves . Take pictures of them go to home depo find identical ones and put on you're thinking hat and get busy .

Thank you. Should I turn off water for the house first? To test if water was flowing I very gently began to unscrew them, re-tightening them when I noticed the water dripping out, so it would seem it's still getting some.

...If so, I'm also curious how I would shut off water to the house.

Main water line should come through basement wall or if its on a slab somewhere up through the floor in a closet. Check the aerator too...it could be plugged from broken down rubber from valves. angle valve handles spinning round and round is not a good sign....good luck.

take off the aerator on the faucet. probably got a bunch of crude it it when you turned the angle stops. or disconnect the water supplies to the faucet.
if they are one pc supplies ( meaning the supply tube is not removable from the valve ) you are better off just replacing the valve.
They seem easy but I know experienced plumbers who have trouble with them sometimes, including myself.
Replace with a 2 pc, valve and detachable supply