As has been said many times. Always have a backup. It can't be said enough. never, ever install a beta on a working Trainz version unless there's a good reason to do so. The AI driving sideways is a known issue with this beta and is mentioned in the known issues list with other things.
If you haven't saved any routes or sessions, you should be able to restore your content intact, but you will need to download the released version again.
Uninstall the beta version.
Download and install the released version from My Trainz under product downloads. Make sure you download the correct version.
Install the program as if you never used it before.
When the installation is done, it will find your current content folder.
NOW THIS IS IMPORTANT!!!
The initial DBR may or may not display the progress bar while it's running. You need to click on the Developer menu and choose Show Client Logs.
This will display the progress as a continuous stream of information and may stop updating if you have lots of content.
If you use a regular hard drive, you will hear the content being pre-cached and verified, and defrag the drive afterwards! I recommend you bring up Task Manager by pressing the CTRL+SHIFT+ESC keys at the same time. You can then watch TRS22.exe (Plus is called that) activity such as hard drive.
Once the DBR has completed, you can tell because there is no longer any disk activity, open up Content Manager.
Change the filter from Installed to Faulty and let it run. This may take a long time if you have a lot of content.
When this has finished, select any content listed, don't panic, right-click and choose view errors and warnings.
Most of the errors should disappear, if not all of them. If they don't then you need to check further.