grub issue
 

i have cent os 5.5 installed in my system. when i started my machine it shows me

grub>


at statup.

It sounds like you didn't install a bootloader. You can either boot from a LiveCD (e.g. https://help.ubuntu.com/community/Gr...talling_GRUB_2) or just re-install CentOS and choose the options to install a bootloader when you do that. (Note that CentOS is now on version 6, so you're installing quite an old version).

Information needed which should help, is this a new installation? If so, were you ever able to boot it? If it is not a new install, what changes were made to hardware/software immediately prior to the problem? Which bootloader are you using, Grub Legacy or Grub2? If you have any Linux Live CD, you could boot it and go to the site below and read the instructions for the bootinfoscript, download and run it and review the outpupt (results.txt file). If you don't resolve the problem, post the file here:

http://sourceforge.net/projects/bootinfoscript/

With Cent 5.5 you are probably using grub1. There should be tab completion at this point. You could try manually loading the kernel/initrd and booting. The following commands may help. (press <tab> and it may fill in the kernel/initrd from the disk. This makes some standard assumptions about your install.

grub>kernel hd(0,0)/boot/vml<tab>
grub>initrd hd(0,0)/boot/init<tab>
grub>boot

If this works and you boot to cent. You will probably want to re-run grub-install.