I was trying to install new kernel in my backtrack which was having kernel 3.2.6. i tried installing 3.8.5.
I refered to book linux kernel in nutshell i followed every step. after i rebooted (i had set new kernel in default as my backtrack doesn't display options to select while booting) it gave me fatal error
FATAL ERROR can't load /lib/module/3.8.5/<some-file>
please tell me what does reside here and when do we copy it?
Depends what <some file> is, why it needs it, and what instructions you followed.
Can you still boot your old kernel?
No. i can't as i already mentioned my back track doesn't offer choosing kernel. it was my mistake i should have check for that option.
Aditionally i checked there's no directory for new kernel's version is there in /lib/modules
it only contains directory for previous version.
I'm unable to access /boot (its not avaiable) otherwise i would have restored the previous grub.cfg
Boot a rescue CD such as SysRescueCD. You will be able to access your /boot partition that way, though you may have to mount it manually.