Transmission

The first thing to do will be to check the transmission fluid level. With the engine off there should be fluid on the dipstick. Next start the engine and check the fluid level again. It should be on or near the full cold marks. You say it is not moving, do you mean you have no vehicle motion regardless of what gear you select or if you rev the engine in gear or do you mean you can put it in drive or reverse but it will not shift but it does move in those gears?

That would be the worst failure mode. If the fluid level is okay and it is clean and doesn't smell burnt then I suspect an internal failure. A transmission shop could tell you more by doing a few tests with a scan tool and pressure gauges but with no motion at all it isn't an electrical failure. More like a pump or valve body issue.