I recently installed ubuntu on a pc alongside windows 8 and something went bad. Whenever i boot from the hard drive, it shows the ubuntu menu to ask which os to boot and when i choose windows 8 it boots and comes up with a screen and it says disk checking then gives two options; one to restart the pc, then the next is advanced options. I have tried every option including booting from a previous save(I was stupid enough not to make one) and the option to un-install windows asks to insert your windows installation media and a put in the disk and it says the disk is in-correct. I need a way to completely format a hard drive with uefi or something including deleting ubuntu. I used windows 8 pro oem.