Sequence dissapered after saving a project

I worked for hours, saving my project continuously. How surprised i was when I opened the project and one of the sequences was just gone. Unfortunately it was the most important one when I had the final product. I am furious, any idea where to find the lost sequence? Can naming the sequence "Sequence 00" be the issue? Back up was made only before most of the adjustments. Thanks for any idea before I start again from the scratch... 😞