It's no problem to get it back.
You will need to boot into RH9 via a bootdisk. The install should have prompted you to do so, you could probably download one at bootdisk.com or I beleive you can use the RH install disk and go to recovery mode (but that is text mode only)
Get to a terminal and become root
and then your root password
which will put you into grub's console.
You will know need to tell grub to install on your mbr and show it your boot partition. To do this however, you need to know what partition it's on. Grub labels partions with two numbers. The first number is the hard drive number (starting at zero) and the second is the partition number (starting at zero). (eg (hd0,0) is my boot partition). If you are unsure where your boot partition is open up /etc/fstab (it is a text file) and look for a partition mounted at /boot (second column) and find the device name for it (first coulmn). If you don't have a boot partition, look for the partition mounted as /.
I will explain how to get this info, if I fail, just post your fstab file and I'll tell you.
For example, my boot partiton is /dev/hda1.
a is the first hard drive, so my drive number is 0. If however it were hdc, and I also had a harddrive at hda but nothing at hdb, hdc would be drive number 1 (not 2). The numbering skips all other devices.
1 means the first partition so the partition number would be 0. hda3 would have a partition number of 2.
Suppose your boot partition is at /dev/hda1.
Then you install specify the boot partition
Install Grub on the MBR with
then exit grub's shell with
You should now have grub when you reboot.
As far as your grub issues, you can fix them all by modifying your grub.conf or menu.lst file, here's mine
grub.conf or menu.lst (depending on distro, I can't remeber which RH9 uses)
title Gentoo 2.4.26-r9
kernel /kernel-2.4.26-gentoo-r9 root=/dev/hda3 vga=792
default refers to which gets booted by default, timeout is in seconds and title is the name for an OS that appears on the screen. The majic of linux is that all the configuration is done with text files so everything is accessible. Just be sure not to make typos on your conf files.