It's my first time installing ubuntu. I have Windows 7 and 8 before in my laptop (Acer Aspire 4752z). After Ubuntu (12.04) installed in my laptop, the Windows boot loader didn't recognize my Ubuntu so I updated grub from a live USB. And after grub updated, Ubuntu was booting perfectly but my Windows wasn't listed in the grub menu. So I follow someone instruction to update grub again. And after reboot, the grub menu didn't show anymore. After searching about this problem on the net and trying to update grub again and again, I decided to delete the Ubuntu partition from live USB. And shortly after, I booted to Windows with Hiren boot and I used mbrfix. But i think it failed. Now i cant show my BIOS setup or boot from DVD or USB. After that, the only screen i can see after booting is: error: unknown filesystem grub rescue>