I have had a problem like that and the reason for odor coming out of just one faucet was because they had another water line teed off of the faucet line that was capped/abandoned and the smell was coming from that line because after I disconnected the abandoned line, the smell went away so I don't know if you would have the same problem or not.
The faucet is clogged
A clogged aerator on the end of the faucet would cause the water flow to decrease in that faucet.
I'm no plumber, but I would imagine that (if the hot faucet is giving you cold water) that the hot and cold pipes leading into the bathroom have been somehow switched.
Someone may have shut off the water to that faucet, or a pipe may have froze, or there may be air in the pipe.
Probably the simplest example in the bathroom would be the gear attached to the faucet handle. It consists of a worm gear which opens and closes a valve, restricting or blocking water flow from the spigot.
Probably the simplest example in the bathroom would be the gear attached to the faucet handle. It consists of a worm gear which opens and closes a valve, restricting or blocking water flow from the spigot.
The problem could be as simple as a clogged screen in your faucet. It also may be a low flow gasket which is in the faucet to reduce water usage. Has this alwys been a problem or is it a new problem?
The break and repair events probably released debris into the pipe. These eventually get caught in the faucet valve and it may have to be disassembled to remove them. check the areator
check for leaks
The shut off valve under the sink, the faucet itself, or most likely, the screen in the end of the spout is plugged. If neither hot or cold is coming out, it is kind of unlikely both shut off valves and both sides of the faucet would go bad at the same time. The screen being clogged would stop any water from coming out. The screen just unscrews out of the spout.
First place to check would be the airator screen on the faucet. The little screen where the water pours out of the screen could be plugged with iron or calcium depending on your water supply or plumbing material. The screen is just screwed in and should be able to be unscrewed by hand or gently with a pair of plyers.
If water gets under a faucet washer it can cause a loud vibration when the water is turned on. You either need to find a proper replacment or get a new faucet.