If you rev the engine in D or R does it bog down like its trying to move or does it rev free and easy?
Will it roll in all gears but park?
If the answer to question 1 is revs free, then its internal transmission issues or not actually in D or R
If the answer to question 2 is yes, then the axle, driveshaft, parking brake, and shift linkage are good and its internal transmission issues.
If its internal, it can be low on fluid, not electrical, filter has popped off, input or output shaft broken, faulty pump.
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