I installed windows 8 on my external hard drive and now, my original OS won't boot. The bios setting is set to booting from external devices and when I disconnect the external HDD and then start the computer, no operating system is detected. The problem is that I cannot find a way to go into the bios to change the setting back to booting from internal drive. I tried every option I found and nothing worked. I tried pressing all the f key and esc and delete. Tried restart and cold start ups. By the way, there is no uefi firmware setting in the advanced start-up menu. The bios setting is set to legacy boot instead of uefi boot.