My John Deere riding mower is stuck in the yard. It has a fresh battery, was running normally and stopped & started several times. The last time I attempted to start it- no response. The lights still work, but no sounds of starting. I tried to push it and it won't push. Yes, I pulled out the lever to release & made sure the brakes were off.

Hi,
Just because the brakes are "off" does not mean they cannot stick on. The hydro disengagement rod will do nothing if not hooked up(I have seen that before.) Look through the right side past the rear wheel/tire(in front or behind) see the action of the rod as well as the disengagement of the drive belt tension.
In a pinch you can remove one rear wheel(does not matter which) and remove the key that locks the wheel to the axle. This will allow the machine to be pushed since the wheel will spin one way and the axle the other on the side you did that on. Of course, jacj up the machine before doing this and do not forget to put the key back in for operation once the cause is found.
Peace,
Clarke