I have some problem in move back file ....... 

I have no idea what you are talking about.Are you talking about .BAK files?  Are you trying to get AutoCAD to save your .BAK files in a different location?Are you trying to move a file from one location to another?It would help if you gave us a FULL explanation of the problem.  Why should we have to guess?

i want to make bake up file for my cad drawing thatswhy i apply movebak command and gave the location of folder. but when i check the bake up file it does not work it does not open........

I don't think you know what you are doing.  You can't open a backup file without renaming it to a drawing file.  You should sign up for an AutoCAD course.

dear its working in my laptop ... but not working in pc ........ now what shoud i do ?

Zuhaib Rajput, maybe you can see the XXXXX.dwg or XXXXX.bak on one of your 2 computers and not on the other, then maybe you open the XXXXX.dwg instead of the XXXXX.bak.
You can rename easily your XXXX.bak to XXXXX.dwg with 2 clics.

dear JOSEPH, there is no problem created in my laptop whaen i m changing extension .bak to .dwg  .... but when i m changing extension in pc ...... its creating problem ....... 

When you use Windows Explorer to see the contents of the folder where your backup files are being stored do you see something like this.....?drawingname.bakAnd when you rename the file does it look like this...?drawingname.dwgYes or No?