If you use some kind of Version Control, you could go back to your last stable version.
If you don't use Version Control, now you have learned why you should.
In a nutschell:
You have a showfile that you are running every week/day. Let's call it "Showfile V1".
When you want to make changes to that showfile, make a copy of your file and call it "Showfile V1.1".
As long as you haven't completed and tested your changes, you use V1 to run your show and do your development on V1.1.
When you are happy with your changes and tests proved that is is reliable, you are going to use V1.1 for your live shows and you create V1.2 for further development.
You could also maintain some kind of Change Log (by making telegram style notes of the changes you made).
If you work this way:
- you never get in a situation that you are forced to complete your changes in a hurry (because the show has to start in xx minutes).
- you always have a version to go back to when you run into unexpected problems.
If you want a good example:
viewforum.php?f=2
If you make regular back ups from the data on your PC, you could also try to retreive your showfile from there.
A QLC Workspace is like a Bob Ross painting: "it's your world, you can create whatever you want!"