Possible reasons:
1. Low transmission fluid level:
* Check the transmission oil level using the dipstick or level indicator.
*Add the correct type of transmission fluid if the level is low.
2. Problems with the electronic transmission control system:
*Sensors, solenoids, or electronic control unit (ECU) may fail.
* Computer diagnostics will be required for diagnosis and repair.
3. Hydraulic system malfunction:
* Problems with the pump, valves or torque converter can prevent fluid transfer and vehicle movement.
4. Wear of friction discs:
*Over time, the friction discs in the transmission can wear out, causing slippage or loss of clutch.
5. Faulty transmission housing or other mechanical components:
* Damage to the housing, gears or shafts may prevent the vehicle from moving.
What to do:
1. Check the transmission fluid level.
2. Contact an auto mechanic for computer diagnostics.
3. Consider changing the transmission fluid if it is old or dirty.
4. If mechanical problems are found, the transmission will need to be repaired or replaced.
Important Notes:
* Do not continue driving if the vehicle does not move forward.
* Have the vehicle towed to a mechanic for diagnosis and repair.
* Regular transmission fluid changes and maintenance can help prevent transmission problems.