grub error 15!! calling for help!!!

I changed my partition table for some reason yesterday.And today when i tried to boot it i got grub error 15!This message shows up before my computer freezes up...
grub 1.5
grub loading please wait...
error 15

i have no idea.i googled for this problem and founds lots of people suggest to read the man of grub which i did.but i still have no concrete idea...

additional: i didn't create a boot floopy...so i cound not got access to the redhat...

please if help is available,let know as soon as possible!!
U help would be greatly appreciated!!

try grub for dos?