I'm sorry to hear that. You could try double-checking your backups by navigating to the physical folder on your computer where the backups are stored. On Windows, those are located at:
Note that AppData is a hidden folder.
If you published the file to Axure Share, you could also download the .rp file from there by logging into the Axure Share web interface at share.axure.com, navigating to the project workspace, and clicking on the gear icon under "Configure" to select "File + Settings". This will take you to the project's overview page where you can download a copy of the .rp file from there.
Hopefully one of these options help to recover your file. If you're able to recall any steps you took prior to the 9 beta crashing, that'll also help in our investigation of the issue. Thanks!