This is the method I use when the actual drawing file is corrupted. At the very bottom of the “Tools” pull-down menu, click on “Options” This will indicate where the temporary drawing files are store. If you’ve been using Autosave, then there should be some files with the .sv$ file extension kicking around in this folder.
Next using Explorer I locate an .sv$ file which was created before you started having problems with the drawing file. Rename this to a .dwg file extension, then open it with AutoCAD. Hopeful you will have something usable, that will save you drawing the whole thing from scratch.
Try another PC. Sometimes another user is able to get the file to recover.: http://www.dwg.viewertool.com/