First I would check the water shut off to the unit just to be sure someone has not messed with it.
If OK shut the water off.
Remove the kick plate.
Remove the supply line from the water valve and check that the screen on the inlet side of the valve is clean.
Have towels and a shallow try handy so you do not get water all over the place when disconnecting the water.
If the screen is clogged clean it, do not remove it from the unit permanently as it is there to keep crud out of the valve which could hold the valve open and cause a floods.