The single most likely reason would be buildup of rust or calcium particles in the valves and inlet. Many showers have a one-handle arrangement wherein the handle controls movement of a ball. That ball has two very small inlet holes, roughly 3mm (1/8 inch) diameter each. If your shower has this type of arrangement (and not a newer maintenance free cartridge) you can turn off the house water supply, take apart the handle and ball device, remove and replace the springs and seats for the inlets, and clean the ball with an old toothbrush and CLR.
If your water heater is very old, or if you have old iron pipes for your water supply, you are likely to experience this kind of problem more frequently.
This is a sign that the Diverter is not functioning.
Most likely, your tub spout is jammed.
It would help to know what brand and if it is a pressure /temperature balance type also AKA scald protection
I use a spray bottle with vinegar. It isn't the best smelling but works and is cheap. You can also soak your faucet heads/ shower heads in vinegar to take away calcium build up.
Faucet water systems offer a higher level of protection than the container based systems. These have built in protection against harmful contamainetns.
Usually acid works the best for me
I tried to use some soap water to clean the glass shower door. It works well.
if you look under the sink, you will probably see a cutoff valve going up to the sink faucet. turn this on. if that does not fix it, then change you faucet fixture.
Search it to google. *troll face*
If there is a shut off valve under the sink, shut it off and take the line off going to the faucet. Turn the valve on slightly to see if there is water going through it. If there is, the problem has to be in the faucet. Either the washer in the hot water side has come off and is plugging the faucet, or if it is a single handle faucet, the cup is bad. Either one is easy enough to fix. Message me back if you need help fixing it.
Material such as plastic works well as a shower curtain because it keeps all the water in the shower without soaking anything up. You also want to make sure it is plenty long to keep the water in.
First off - be on the outside of the shower and screw with it clockwise and anticlockwise and see what happens. Works every time.
Yes however a lile soap works even better.
From the Delta page. "The faucet works using something called capacitance. This is the same technology that is used to make touch screens work. There is a low voltage electrical current that flows across the handle and spout of the faucet. As soon as this circuit is interrupted by skin contact water begins to flow."