I previously installed Ubuntu on a computer that had Windows XP on it and got it successfully to run alongside it. (access both OS systems) Now I installed Ubuntu again on my MSI notebook with Windows 8.1, and I cannot access the GRUB without hitting escape on startup, and even then, I can no longer open windows. Before all of this, I created a recovery point, file history and saved a back up on a external hard drive incase I did anything wrong. Now how can I revert my computer back to it's state before installation.