Recover Lost AutoCAD File

1. Open the Autosave folder.
   • On Windows: By default, it is in the Temp folder. You may open it by typing %tmp% into the Start menu.
   • On macOS: By default it is /Users/<username>/Documents/Autodesk/Autosave.
2. Turn on filename extension visibility if not shown (see To Display filename extensions in Windows). 
3. Look for a file with the same name as the one to recover, a time stamp code, and an SV$ extension.
4. Change the SV$ extension to DWG.
5. Open the file in AutoCAD.

More information: https://www.autodesk.com/support/technical/article/caas/sfdcarticles/sfdcarticles/how-to-recover-lost-work-due-to-a-crash-in-autocad.html