I think I helped you out today during office hours. Sharing highlights from our debugging process in case others find it helpful:
Check the "Releases and history". You can revert to any previous state from this list. It may be worthwhile searching further back to see if your work was saved in an unexpected version.
If you can't find the version there, you can use URL parameters to travel back. Use the ?_historyOffset=10 parameter in your app's URL and change the number as needed.