I'm sorry to hear about your save data. The game stores it's data in local storage as a cookie so it's possible that it got wiped by mistake. If you want I can try to get hold of a save file that's near to where you were, just send me a message on discord for this.
The export is currently bugged on some browsers (Chrome / Edge) but there is a workaround to get your save data which you can find at: https://itch.io/post/5873086
As a side note the Itch.io client seems to allow you to download the game and the export works correctly on that version. It does seem to run the game on an emulated browser but as far as I can tell it works offline also.