Transmission not working properly in reverse and neutral?

Assuming there are no codes, the thing I would start with is checking the shift cable to make sure it is adjusted properly.

Here is a guide that will help with codes as we should check to make sure we don't have another issue:

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

If there are none, then please see the info below on how to replace and adjust the shift linkage.

I would start with this and if that is fine then we need to check the fluid and change it if it is low or dirty.

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

Please run through this and let us know what questions you have. Thanks