Unfortunately there’s no way to get it back, at least that I know of.
One time I spent an hour coding and my son hit the keyboard and backed me the whole way out, I completely lost all my progress. My sweet child taught me a lesson that day…
Save. The Script. OFTEN!!!
I make it a point now to save the script after coding around 100 lines. If I’m doing intense directing with overlays then I save more frequently, even without grabby hands near me. My computer is so old and slow that one of these days it’s just gonna crash on me.
So…
I continue to save often 
But in all seriousness, I’m really sorry this happened to you and I completely understand the frustration when losing so much hard work!!