2002 GMC C1500 TRUCK WILL NOT MOVE WHILE RUNNING IN GEAR

I WAS DRIVING ALONG AT 65 MPH WHEN THE RPMS REV UP. THE FIRST THING I DID WAS CHECK GEAR SHIFT TO SEE WHY IT POPPED INTO NEUTRAL, IT WAS IN DRIVE AND COASTING TO A STOP. I COULD NOT GET ANY MOVEMENT OUT OF ANY GEAR, JUST LIKE BEING IN NEUTRAL. WHEN CHECKING THE FLUID LEVEL THE LEVEL DIDNT MOVE WITH ENGINE OFF OR RUNNING. DID PUMP GO OUT AND WHY SO. HAD PROBLEMS WITH LOCK UP IT WOULD GO OUT OF LOCK UP, DURING CRUISE SPEED ON FRW, BUT LOCK UP WHEN CLIMBING HILL OR USEING KICK DOWN. THE LOCKUP WAS WORKING BASSACKWARDS OR SO IT SEEMS. THANKS AL