Transmission reverse gear not engaging

Good morning,

If you have normal forward gears and no reverse gear, it is most likely a failure inside the transmission.

I would drain the fluid, add new fluid and inspect the fluid to be sure there is no metal in the fluid or chunks of material. A band and a clutch are used for reverse so it could be either one causing the issue.

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

Roy