ubun2

I have two operative systems. Windows xp and Ubuntu 9.10 both worked good, but a week ago I can't get ubntu, when I turn on my lap top display a mensage where said :
                          GNU GRUB  version 1.97  beta4
follow said use tab key for possible command  bbut when I push tab key display differet comand but anyone answer
What can I do
Luis M Castillo
If someone could help me my email is miguelcastilloc@gmail.com