I wanted to make the grub screen a little more appealing so I got the Grub-Customizer app and tried to add a background image. Once I did that I rebooted my pc to check it out but then I found out I couldn't get back into either operating systems. The only reason I am able to ask this question is because I booted from the ubuntu cd. Please is there anything I can do?
I have the same issue. The only way I solved it is by installing "boot-repair" on the live CD and go to advanced options and reinstall grub. After you have repaired it, do NOT go near grub customizer again because it will break it again.
Here is a link that will help you install "boot-repair" https://help.ubuntu.com/community/Boot-Repair