Help with my stuck garbage disposal; I've tried everything!?

My garbage disposal just "hums". I checked the breaker box (ok), I've pushed the red restart on (nothing) I've put the wrench in the hole on the bottom--I was able to turn it clockwise a full circle, and counter-clockwise 1/2 a circle. I put the broom handle in & moved it a little each way. I SEE nothing in there. I use it very sparingly for very SMALL mushy things only! (no coffee grounds, veggies, grease, etc.) Help!