Please help me..

I have two hard disk in my laptop..window 7 and ubuntu.. I have problem to back in option menu..because i enter one of the list of ubuntu.. In option menu,,have a list which operatg system i can choose between ubuntu n window7 but the list stil have another menu for ubuntu..i make mistake to choose the another list of ubuntu..and now i have to fix the command line that have grub rescue..

like this :

        error : no such partition
        grub rescue >

i dont have any idea to fix this problem..i try the another step that i see at the other question but still dont have any answer..this problem is just i enter the another list but do not have any kernel,problem or somethg like that..