Can't Open Cubase Project

I was working on a track, made a couple of changes, saved and closed it. The next time I tried to open the file I got a message" invalid project file" and couldn’t open it. Luckily I backed up the project but I don’t have the most recent changes that I made. Not sure how to get it opened. Any help would be much appreciated. Thanks

You should just be able to double click the .bak file.
If that doesn’t work, in the Open Project dialog box change the filter from .cpr to all files (.) and select the .bak file.

Thanks, I’ll try that.