To reinstall the operating system or run the Live CD, you must boot your computer from the optical disc drive. The order of checking devices for boot sectors is set in the CMOS Setup utility. Not finding such a sector, the BIOS tries to boot the computer from the next priority device.
Instructions
Step 1
Enter the CMOS Setup Utility. To do this, restart your computer and as soon as the BIOS screen appears, start quickly pressing the Del or F2 key. Which one will work, determine empirically. The computer may need to be restarted twice to do this. The first of these keys is more often used to enter CMOS Setup in desktop computers, the second in laptops, but there are exceptions to this rule.
Step 2
When the utility starts, find the Boot Sequence item in its menu structure. Its location depends on the BIOS manufacturer. In some versions of the utility, boot devices are designated as 1st Boot Device, 2nd Boot Device, etc. By selecting any of them, you can assign the corresponding physical device: a disk drive, an optical drive, one of the hard drives, etc. In other versions of CMOS Setup, a list of all available physical devices is displayed on the screen, and using the PgUp and PgDn keys (sometimes other) they can be moved up and down, changing the priority.
Step 3
Adjust the setup order so that the optical drive takes priority over all hard drives.
Step 4
Insert a bootable CD. Press the F10 key and then Enter. The computer will start to reboot. If the disc is read, the download will start from it.
Step 5
After reinstalling the OS or working from the Live CD, restart your computer, go to the CMOS Setup utility again and change the boot order to one in which the hard disk takes precedence over the optical drive. This will reduce wear and tear. You can also set a strong password to enter the utility, and then an attacker will not be able to boot the computer from his own CD without opening the case of the system unit. Indirectly, this can help to avoid unauthorized reset of another password - to enter the operating system itself.
