Check for an object in the seat tracks blocking movement. A napkin, a coin etc. .
sounds like shifter cable busted... pop the hood and look at drivers side, have another person move the shifter so you can locate the cable... then find the arm coming off the transmission move it all the way one direction it will be either park or low range and that should get you moving again...
Try pouring gas derect in carb if it still won't start pull plug and check for spark . If it runs for a little then shuts off,drain carb and check for clogged fuel line, or filter sometimes a toilet plunger over the open gas tank can get sludge moving so you can get it out, or air pressure don't use vacuum cleaner it will blow .
Every engine I've had a chance to play with uses TDC as the reference point for setting timing both ignition and valves.