Wear, heat, driving style, poor design, failure to keep the fluid level up and changed. Pick whatever seems appropriate to the situation.
The engine, the transmission and the operator.
car can be started an does run fine.
Poor driver or bad transmission.
what is the problem when the car will not go in drive or reverse? and the transmission fluid is still full
It would be a transmission issue, not up shifting. If the engine is in "limp mode" it will not accelerate over a set mph.
what can cause your car not to shift gears besides the transmission
You have transmission problems, see your local transmission shop.
The engine revs and car doesn't move.
Inside the transmission, above the transmission pan.
A bad transmission.
Transmission Control Solenoid
Slippage in the transmission or a bad torque converter