Saved a project then lost everything when exporting to MP3

I had a project file that had the background music synced and leveled exactly how I wanted, so I opened that and saved it as a new project.

We then recorded about 30 minutes of audio.

I saved the project, then exported the audio before editing as an MP3. I received an error that I can’t recall.

All of the recorded audio was then missing.

When I closed and reopened the project, the audio was still missing.

There are still .au files in the _data folder.

Is there any way to restore this? I can’t seem to figure it out. Thanks!