How to restore a drawing from a backup file and move backup file to drive C
- In Windows Explorer, locate the backup file identified by the .bak file extension.
- Select the file you want to rename. You do not need to open it.
- Click File menu Rename
- Enter a new name using the .dwg file extension.
- Open the file as you would open any other drawing file.
Now for moving backup file in to your drive C if you’re working in a Server file folder and want to change the destination directory simply type the command MOVEBAK

As the image above for example I made first a folder name bakfile in my drive C after that, I go to my Autocad type the command movebak then type the C:\bakfile and enter. And if you want to get back or restore from old destination type the . (period) for none.