Hi, you could try the following steps, if you have not done so already. Some of these steps may seem like common sense, but it's for people to forget about checking the least expensive part to replace first, so if some of the steps are those that you have already tried, then feel free just to skip through to the ones you have not tried already.
Make sure the power cord is plugged firmly into the outlet.
The steam mop will not start if it the power cord is loose.
Check the fuse box or circuit breaker connected to the
outlet the steam mop is plugged in to. Replace any blown fuses. Reset
any tripped breakers.
Check the water tank if the Shark steam mop will not produce
steam. Add water to the tank if it is empty. The mop will not make
steam without water in the tank. To fill the tank, turn the tank cap
counterclockwise and lift it up to remove it. Set the filling funnel
into the tank opening. Pour water through the funnel into the tank until
the water level reaches the "Max" fill line on the tank. Replace the
Inspect the microfiber cleaning pad if the steam mop is
leaving water on the floor. If the microfiber pad is too wet, it will
leave water on the floor. Unplug the mop from the wall outlet. Replace
the microfiber cleaning pad. To replace the pad, move the latch strips
out of the hooks on the mop head. Pull the pad off. Set the new cleaning
pad on the mop head. Hook the latch strips onto the hooks on the mop
Use distilled water if the steam mop is leaving white spots
on the floor. Hard water may cause white spots to be left.
If none of the above work, then is it something that you purchased recently, and is new? If you did, then it could still be fixed under the manufacturer's warranty regardless of whether or not the original length of the warranty has expired. This could be due to the fact that you have received a product that has some sort of manufacturing fault, rather than it stop working through misuse by the user.
If it's a common problem, then you will more then likely be able to return it to the manufacturer and have it replaced for a new one, let alone repaired :-) - This only applies to whether or not the item is New though :-).
Hope this info helps