I have windows 8. I can't get to boot menu and I have formatted partition which had Ubuntu on it.
- I need to get to windows.
Can any one please help using the GRUB prompt as I have tried all other methods?
As mentioned in one of the comments, if you formatted the partition that contained the MBR, then you won't be able to access your Windows System, because the place where the information about loading OSs has been swept away.
Since it seems that you are not longer interested in having Ubuntu in your machine, you'll need to use your Windows Repair CD, in order to restore your MBR properly.