Hello Scrilopolis and welcome to the ArtRage forums Though I wish it could have been under better circumstances!
Sadly if the painting had at no time been Saved then no, there is no way to retrieve it.
Whilst it can’t help you now, I would recommend going forwards, that on starting any painting make sure Store Backup Files is activated in Preferences > Advanced, and that you make at least one manual Save right at the start of the painting even if you haven’t done much more than create the canvas.
But as I say, regretfully there is nothing more that can be done this time around