Currupted Grub, how do I repair it

I installed Linux Mint last night, and today, managed to corrupt the grub partition (I think). When I boot, I get the grub prompt (and some error message, I think). Right now I’m booting off the Mint CD. I have the Ubuntu 9.04 live CD also, if that helps.

I’ve tried to follow directions on repairing it here and here . I can’t follow the first, and for the second, Step 3: Install GRUB to the MBR: doesn’t work. For the first link, find /boot/grub/stage1 doesn’t work either.

I’ve gone partway through reinstalling Mint, but it wants to install another partition of Mint, not overwrite the existing one. There didn’t seem to be a way to tell it to overwrite the Mint partition.

If it helps, the partitioning from the first step of the second link is given below.

sda1 is Windows XP, sda5 is a FAT partition, and sda7 is an existing Ubuntu partition. I don’t want to harm any of these partitions. sda9 is the new Mint, which is only marginally altered, and may be sacrificed. I guess the others are swap partitions, or maybe one is the grub partition.
mint@mint ~ $ sudo fdisk -l

Disk /dev/sda: 120.0 GB, 120034123776 bytes
255 heads, 63 sectors/track, 14593 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x0004fa98

Device Boot Start End Blocks Id System
/dev/sda1 * 1 3560 28595668+ 7 HPFS/NTFS
/dev/sda2 3561 14593 88622572+ 5 Extended
/dev/sda5 4866 12160 58597056 b W95 FAT32
/dev/sda6 12161 12409 2000061 82 Linux swap / Solaris
/dev/sda7 12410 14496 16763796 83 Linux
/dev/sda8 14497 14593 779121 82 Linux swap / Solaris
/dev/sda9 3561 4803 9984334+ 83 Linux
/dev/sda10 4804 4865 497983+ 82 Linux swap / Solaris