Transmission will not go into gear

When you say gear do you mean both no forward or reverse? Can you hear any noises ? If not I would check for codes to see what comes up.

Here is a guide:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

If no codes are present check the transmission for leaks and if so check the fluid level. Here are some diagrams to help you see how to do it (below).

If the fluid level is okay and there are no codes the next step is to check the gear selector position switch.

Here are the transmission wiring diagrams (below).

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

If the switch tests okay chances are it is a major mechanical problem such as an input shaft failure.

Please let us know what you find. We are interested to see what it is.

Cheers, Ken