Where do AutoSave_ files go after saving model

When your model is set to auto save every 5 min, the AutoSave file is usually located in the same folder or location as the original file. And I understand that when you manually save your progress, the AutoSave_ file disappears, leaving only the SKP & SKB files. My question is where does the AutoSave_ file go? Does the computer simply purge itself of the file or is there some sneaky sub folder somewhere deep in my computer where it stores these files?

I was working on a model for 6+ hours last yesterday, i stepped away from my computer around 4pm to make dinner and clean up, only to come back later to my computer updating windows (without my permission) and restarting the laptop. The model i was working on was closed out, and there was no AutoSave file in the folder and the last manual save was made around 2pm so I lost 2 hours of work. I looked everywhere for the autosave file.