Audacity file saved as flat with no waves

I saved my edited podcast episode onto my External hard drive but the file has no waveform at all. What can I do to retrieve this file?

Which version of Audacity?

We had a nasty bug in 2.2.0 and 2.2.1 where if you used “Save As” to save to the the current project rtaher than the simple “Save” - then the project got irretrievably flat-lined.