Note: Accessing the internal pump usually requires tilting the machine back and removing the bottom panel. If you aren't comfortable with this, it is time to call a professional.
If the filter is clean and the dishwasher still won't drain, the hose is likely clogged with greasy sludge. How to Unclog a Dishwasher Drain in 5 Steps - Whirlpool how to unblock dishwasher drain pipe