so I’ve been working on a project for 6-7 hours, without saving (I know, wrong) then D5 crashed. now, I can’t recover it through File> Version History obviously, but is there any other way?
Sorry to hear that.
To use autosave, the project needs to be saved once. A project that has not been saved will not trigger the Auto save function. Generally, it’s hard to retrieve the file in this case. 
However, these are the steps of how a user who once lost his files due to a computer crash got his files back, and I suppose you could probably give it a try.
- Changing the .bak file into .Drs and pasting it in the main file.
- Opening that file and inside that open “history version”
- Saving a correct version
- Open saved file into a new one and saving again.