How do I use GRUB to boot linux at grub prompt?

Hi my name is David.
I have recently partition my harddrive to install linux,which went well I might add. Any way one day I boot my pc and found that I could no longer choose which OS to boot into. I have a "GRUB"promt: I have done some hard work and finally use chainloader to boot into my windows OS. I try to do the say to boot into Linux but had no luck. If any one has any knowldge of GRUB I would be very greatfull.

Hi Dave,
In mandrake 7.1
You log as root.
Go to Drakeconf, it's on the desktop.
Go to Drakeboot, & you have the choices you want.

I don't anything about any other favor of Linux.
I'm lucky I found the on switch for my pc today.
Also if you've seen my pants, e-mail them to me.
TIA

derek

Thanks Derek-
But what do you mean it is on my desktop? I can't see anything expect the GRUB: Promt: What should I do.I have use this command and has gotten this far:
kernel (0,0)vmlinuz/boot/dev/hda2

Kernel Panic

no boot disk
at the prompt try kernel (hd0,0) /boot/vmlinuz root=/dev/hdx where x is the partition where vmlinz is.

I have try this"try kernel (hd0,0) /boot/vmlinuz root=/dev/hd2" It started to boot but then the Kernel panic and I could not go any further. What has happen and is their a way to get in by useing the xstart command?

Hay guys just upgrade to RH 8 and dual booting with XP fro about several mounths now, things are going great ,but when I added a external hard drive to my XP system and reboot my system I was greated with a grub prompt: I log into Xp with chainloader +1 and all was well but then reboot to login to Linux 8 and was not able to do so with any of the commands that I know of.

To make a long story short : How to I log into Linux useing Grub?

Thanks