query regarding grub

[Tanmay Nath]

hi,

I am new to linux.I had installed ubuntu on my laptop.It was working good.I made an upgradation.but since then it is not booting and every time it show an error message with 

 grub rescue>
i tried many commands but it says unknown command.I do not have any disk to boot from it.I have installed win-7 on my c drive,my D and E drives have my important data while i have installed ubuntu on my F drive.I need to boot my system so that it can work properly.Kindly provide me steps so that i can boot my laptop.

 

Thanks
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Regards,

Tanmay Nath