(Solved)
I also have ubuntu edgy installed.so i mounted debian etch in ubuntu.
then i extracted debian version of dpkg() into a folder.then i manually copied

each files to the corresponding debian directories.
then i chrooted to debian via ubuntu.then i did
Code:
~#dpkg-reconfigure dpkg
this way dpkg is registered in debian's database.
That's all folks.Ahem...never try again this...U ppl also not.
