I have faced this problem before. I want to compile a Device driver module , simple thing as hello world for my kernel. I want to use the headers instead of downloading t entire source.

I do this sudo apt-get install kernel-headers-$(uname -r)

Reading package lists... Done
Building dependency tree      
Reading state information... Done
E: Unable to locate package kernel-headers-2.6.38-13-generic
E: Couldn't find any package by regex 'kernel-headers-2.6.38-13-generic'

How in the world shall I ever get these headers. Regards
Sraddha