Hello, my dear friends.
We always store the most important data on other HDDs! Not on C:
HDD is a hard drive, and "drive" C is just a partition on it.
5) We leave only CDROM (This means the boot will be from it)
Everything else is Disabled. BIOS versions are different, but the principle is 1.
12) Soon your computer will restart. At this point, you must press (hold) Delete again. Enter the BIOS. Go to Boot again, press Enter, select BootDevicePriority, press Enter, and remove CDROM. Leave only HDD. Disable everything else. That is, the boot will now be from your hard drive.