No modo de recuperação, use o CD-ROM
bash-3.2#fdisk -l
bash-3.2#mkdir /mnt/sysimage
bash-3.2#mount /dev/sda1 /mnt/sysimage
bash-3.2#cd /mnt/sysimage
bash-3.2#ls
bash-3.2#grub
grub> root (hd0,0)
grub> setup (hd0)
depois reinicie
no shell do grub:
grub> root (hd0,0)
grub> kernel /vmlinuz-2.6.18-194.el5 ro root=/dev/sda2
grub> initrd /initrd-2.6.18-194.el5.img
grub> boot