Hitachi Bread Machine Won't Knead?

It could be a number of issues - my first guess would be a broken belt. You can check it by unscrewing the screws in the legs of the machine, then the other screws holding on the plate. After removing, look at the belt. If it is broken, sometimes you can find a replacement like I did on eBay. It may also have just come off. If so reattach with the nubs on the outside. It is also possible that your kneading blade (assuming you attached it!) is stuck in the pan. If so, soak it until it can be removed, then start a new recipe.

Or it is possible the kneading blade shaft has lost lubrication and soaking the blade won't fix it.

You can google how to re-lubricate it. If your kneading blade is not moving at all-you can test it by starting a bread cycle with no ingredients and observing with a flashlight showing into the window-if not moving STOP the cycle because you will likely break the belt. All of this is assuming your circuitry in the machine is working.