notepad.exe doesn’t create recovery or temporary files of any kind.
If you left your computer on but idle for a very long time, there is a very slight chance Windows may have paged out
notepad.exe‘s memory to the page file. You should power off your system immediately (“hold power button for 4 seconds” power off), boot this system with a live CD, and copy the
pagefile.sys to another system, and search through it for fragments of your file.
If you are using a Linux boot CD you can try using a hex editor to see what you can find. You will need to know at least some of the contents of the file as searching through the 4GB, 8GB etc. of your page file (if your system is relatively modern and has that amount of RAM) is impractical. Also, parts of your file may be in disparate locations in this file and there is no way to really string them together. Good luck, you will need it.
Use a different text editor if you want something that saves notes automatically.