how to recover the closed work without saving in autoCAD

The most natural thing to do first is to go and restart AutoCAD. When you quit AutoCAD and reenter, hopefully you’ll see the Drawing Recovery Manager.
If you do not see the manager, it can be opened by typing DRAWINGRECOVERY. This is only a feature of AutoCAD 2006 and newer versions. If you are using an older version of AutoCAD you will have to go find the files manually.
First of all, where are the Autosave files located? One file type, mentioned earlier, is the SV$, the Auto Save file. The location of these can be found by opening up the OPTIONS box and going to the Files tab. The path listed under the Automatic Save File Location is where the files are located. By default this is located in the Windows temporary directory for the user in Documents and Settings.
You will need the view for hidden folders enabled to access this folder in Windows. While enabling the view for hidden folders, it's useful to it’s useful to show extensions for known file types so that you can properly rename the files to DWG. To do these, open up My Computer or Windows Explorer and go to the Tools menu->Folder Options->View tab and uncheck the box next to “Hide extensions for known file types” and hit the radio button for "Show hidden files and folders." Now you can browse through Windows Explorer to the location of the Automatic Save Files. There should be a .SV$ file in that location with a name similar to your .DWG. Change the file extension from .SV$ to .DWG and open the drawing in AutoCAD. Review the file to ensure that all of the data is there.
The other kind of file that will be useful is the BAK file. This file is actually a copy of the file before the last save. This means that the first time that a file is saved, no BAK file will exist. The second time a drawing is saved, the BAK file will be created containing the information from the first save. These files are created in the same directory where the drawing is located. BAK files will only be created if the setting to create BAK files is toggled on. This can be found in the OPTIONS box under the Open and Save tab, “Create backup copy with each save.” Change the file extension from .BAK to .DWG, rename the file to something different than the original, and open it up in AutoCAD.
Compare the .SV$, .BAK, and the original .DWG to determine which is the most up-to-date, and that it contains all of the drawing data. Retain a backup of all of the original files, and rename the appropriate file to the original DWG name. Finally, there’s a chance that the drawing is corrupted. After saving the drawing run the AUDIT command choose YES to fix all the errors. You should now be ready to continue drawing.
Some particular commands tend to crash the program more than others like hatch and 3d orbit. It is a good idea to QSAVE before you run these commands, or any others you find that crash the program.
I wish it will help you. Answered Feb, 20 2011

Brett said it perfectly. When you save the drawing, do a save as, and pick 2007 format instead of 2010.
You can also set up your autocad to always save in that version. In auto cad, type "options". Under the "Open and Save" tab, in the top left corner, under "File Save" select the version you would prefer to save your drawings in. Answered Mar, 23 2011

You can try this tool:
Try RECOVER command or go to folder for autosave, you see path with Options command > tab File > Autosaving path ex.
C:\Documents and Settings\Administrator\Local data\temp\

Open in explorer this path, order file by data and found .bak or .sv$ file. Name is little different from original name, try copy a file .bak (or .sv$) in other folder, rename extension in .dwg e try open this file. Sometimes you can recover previous version of your drawing Answered Apr, 17 2011

well,it's easy,use Chrome browser.

Recover, Restore or Reopen Closed Tabs In Google Chrome

google chrome however has a feature which allows you to re open the last closed tab just by right clicking in the opened tabs and then select Reopen Closed Tab as shown in the image below.

 

This extension you can easily reopen previously closed tabs. There is no limit on how many tabs can be remembered. It is kind of a mix of the "recently closed" bar on the New Tab page and the History page.

 

ALSO,this can be as helpful too

4 Ways to Recover Closed Chrome Tabs and Windows

Answered Aug, 12 2010