If water is draining slowly or not at all, the floor drain or sink trap is most likely clogged with hair and dirt. The good news is you can usually fix this yourself.
Clogged floor drain
Remove the grate covering the drain.
Take out the drain cup inside the drain (some need to be twisted, others lift straight up).
Remove hair and dirt and throw it in a trash bag.
Rinse the drain cup with water.
Put the drain cup and grate back in place. Make sure the cup is fitted properly. This prevents bad smells from the drain.
Clogged sink
If the water drains slowly or stops completely, the problem is usually a blocked water trap (U-bend) under the sink.