I have windows 8 installed in C drive (by default from Lenevo) & Ubuntu I have seperately installed in another partition. When I start my computer it leads straight to the Grub loader. There I can see both options of loading Ubuntu as well as loading Windows 8. when I select Ubuntu, it works fine but when I select Windows 8 option, then it leads straight back to the Grub loader itself. Hence I am unable to boot into Windows 8 via the Grub loader (the only way I boot into windows 8 is the one touch recovery button).
Boot Ubuntu. Try opening a terminal by holding down CTRL and ALT and tapping T and then issue the command
This should find your windows 8 installation again. If this doesn't work it's possible you've overwritten your Windows 8 boot sector which you would need to repair with windows 8 media and then reinstall grub (making sure you don't overwrite the windows boot sector again) so you can boot ubuntu.