Wont Move in drive or reverse why?

Can I ask if the gear range selector is lighting up? You could have a bad gear range sensor here is how you can replace it. Check out the diagrams (Below). Please let us know what happens.

If when reving the engine up in drive the vehicle does begin to creep forward and the fluid level is fine, then by all means drain the fluid, drop the pan and change the filter, clean the pan, put it all back together and fill with new fluid and try that.
If though while revving the engine it does not move at all, the fluid is full and not burnt, check to see that the transmission shift lever is moving when shifting the shifter and if not, check if the shift cable maybe broke or if the shifter just needs adjusted so it properly selects the gears fully at the shift lever.

Did the check engine light come on? Are you sure the trans fluid isn't over full? this guide can help

https://www.2carpros.com/articles/automatic-transmission-problems

Please run down this guide and report back.

Since you lost both forward and reverse and there is no light on, either the linkage has come apart, you lost line pressure, the range sensor is bad, or the Trans Control Module (TCM) is bad.

Good afternoon.

The reverse is the key. There are no electronic controls for the reverse application. It is controlled mechanically.

https://www.2carpros.com/articles/automatic-transmission-problems

You have either a bad torque converter or front pump in the transmission.

It will have to be removed and inspected for the failure.

Roy

The pump, yes. You would need pressure gauges and need to access the plug for testing the pump pressure. If you have no pressure, then it could be either one as the torque converter turns the front pump.

Procedure below.

Roy

Line Pressure Check

Special Tools
* J-21867 - Pressure Gage
* J-21867-65 - Pressure Test Adapter (5.3 Only)

For equivalent regional tools, refer to Special Tools (See: Automatic Transmission/Transaxle > Electrical / Mechanical Repair).

Note:
* Before performing a line pressure check, verify that the pressure control (PC) solenoid valve is receiving the correct electrical signal from the PCM.
* Some conditions may be intermittent, therefore this test should be performed at least 3 times.

1. Install a scan tool.

Warning

Keep the brakes applied at all times in order to prevent unexpected vehicle motion. Personal injury may result if the vehicle moves unexpectedly.

2. Start the engine and set the parking brake.
3. Check for a stored Diagnostic Trouble Code (DTC).
4. Repair the vehicle, if necessary.
5. Check the fluid level. Refer to the Transmission Fluid Check (See: Fluid - A/T > Component Tests and General Diagnostics > Transmission Fluid Checking Procedure).
6. Check the manual linkage for proper adjustment.

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7. Turn the engine Off.
8. Loosen Exhaust cross-over pipe to allow attachment of J-21867-65 - Pressure Test Adapter (5.3 Only).
9. Remove the oil pressure test hole plug and install the J-21867 - Pressure Gage and the J-21867-65 - Adapter if used.
10. Put the gear selector in PARK range and set the parking brake.
11. Start the engine and allow the engine to warm up at idle.

Caution: The total test running time should not be longer than 2 minutes. Running the test longer than 2 minutes may damage the transaxle.

12. Access the PC solenoid valve control test on the scan tool.
13. Increase the PC solenoid actual current from 0 to 1 amps in 0.1 amp increments. Allow the pressure to stabilize for five seconds after each pressure change. Read the corresponding line pressure on the J-21867 - gage.
14. Refer to the Line Pressure (See: Automatic Transmission/Transaxle > Pressure, Vacuum and Temperature > Line Pressure) specification table. Compare the data to the table.
15. If pressure readings differ greatly from the table, refer to Incorrect Line Pressure (See: Automatic Transmission/Transaxle > Symptom Related Diagnostic Procedures > Incorrect Line Pressure).
16. Shut the engine OFF. Remove the J-21867 - gage and J-21867-65 - adapter if used.
17. Apply sealant GM P/N 12345382 (Canadian P/N 1095348) to the oil pressure test hole plug.

Caution: Refer to Fastener Caution (See: Vehicle > Vehicle Damage Warnings > Fastener Caution).

18. Install the oil pressure test hole plug and tighten to 12 Nm (106 lb in).
19. Re-tighten the exhaust cross-over pipe (5.3 only).

Good morning,

The first thing I would do is drop the pan and change the filter to see if it has debris that is preventing fluid to get to the front pump.

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

Beyond that, it is an internal failure that will require removal and inspection.

https://www.2carpros.com/articles/automatic-transmission-problems

Roy

That is normal wear and tear.

Could be but it will have to come out and be inspected. It could be the drum or the front pump or the torque converter.

Roy

Yes you would. That's why I think it's the front pump or the torque converter.

Roy