Will only go in reverse

Hello,

First connected a codes reader to it to see if you have any codes that will let you know that a transmission speed sensor or control solenoid has gone out.

Here is a guide to get you started.

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

It sounds like you have a 1st gear shift solenoid that needs to be replaced, you will need to remove the transmission pan to do so.

Here is a guide that might help

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

Please run this test and get back to us so we can continue helping you.

Best, Ken