Recently I was using Linux Mint dual booted with Windows 10. Then I decided to install Ubuntu 12.10 64bit in space of Linux Mint. I successfully installed it by using the Mint Partitions.
First Problem : Laptop didn't show GRUB menu and instead directly loaded Ubuntu without showing an option for Windows.
Tried Solution : I solved this problem earlier too using boot-repair from the ubuntu live usb but this time it showed some errors. Then I ran some command on terminal after looking for the solution online which formatted my whole 500GB hard disk.
I then used my ubuntu live usb to boot and created a partition table using GParted. Created a partition of 50GB (/root) and 10GB (swap area) and 5MB(bios-grub, in case it is required).
Installed new ubuntu in that partition. Current Problem : Even the gparted shows correct partitions in my hard disk in ubuntu live usb but the bios boot menu doesn't shows it. It checks media and shows "Default Boot Device Missing or Boot Failed "
I can still use my ubuntu live usb. I tried boot repair again but it showed error. (paste.ubuntu.com/14239561)