I am not a repairman but I had the exact same thing happen to me with a Whirlpool dishwasher that is 4 years old. Water would fill the base, clicking sound, then humming, but no washing, hit the 'Cancel' button and the water would drain out.

Your pump motor is out. There are instructions on how to check this attached to the back of the metal facing at the base of the dishwasher. Unscrew the 2 screws holding the facing and on the back of it there is a diagnostics sheet. This will tell you how to check the pump without having to remove the entire dishwasher.

The pump motor will run you around $130.00 online. The instructions to replace it are with that diagnostics sheet attached to your dishwasher. If you do not have that sheet you will have to search online how to replace it. I have very little do-it-yourself experience and I was able to follow the instructions and replace the pump motor. It is an involved process, however, which will require taking the dishwasher out from under your counter, turning it on its side, and getting water everywhere. If you are prepared to deal with that you can do it yourself and save a couple hundred bucks.

But a brand new dishwasher is only $400, so that decision is up to you! Hope this helps!