Dishes not cleaned
When ever I hear of a dishwasher "suddenly" not cleaning properly, with spots on the glassware and soap not dissolving:
-If the spots are white patches, you can suspect the DW detergent powder. Go buy a name brand of detergent powder and I bet you will see a dramatic improvement. You may need to run a cycle or two with white vinegar added (up to two cups added after the DW starts, fills and begins to wash.)
-If the spots are a film / slime, you should suspect that the heating element. For the dW to be effective cleaning and rinsing clear,the DW needs to raise the water temp during the ~wash~ cycle (after the detergent dispenser has magically opened. After the heating element has been replaced, you will see an immediate improvement.
-If you had reported food debris sticking to dishes, (which you didn't), the first thing to do is clear the holes in the wash arms, then open the sump area , remove the filter assembly and inspect closely with a flashlight to locate blocking debris. (watch out for broken glass!) Inspect the impeller and make sure it is not damaged. If after assembly, the cleaning is still poor, it is time to replace the wash pump / motor assembly.
Good Luck! Ask more questions as needed!