If your computer begins displaying the message, “DISK BOOT FAILURE INSERT SYSTEM DISK AND PRESS ENTER” or “No system disk,” it means that the PC cannot start because it cannot find the operating system (OS). Disk boot failure can be the result of many possible causes. This how-to will walk you through the most common ones and show you how to solve the issue in each case.
Disk boot failure is sometimes caused because a CD or DVD has been left in the disk reader. You should begin by checking if this is the case and removing the forgotten disk if it is. Then, restart your PC.
If doing so has not solved the issue, it is possible that your BIOS boot sequence is incorrect. To fix this, enter the BIOS setup and modify the boot sequence so that the PC gives preference to disk C: during startup.
You could also be seeing this message because you've recently installed a new hard disk. This is normal, and is easily repaired. You simply need to insert the system installation CD (usually Windows) into the PC, then reboot. When doing so, make sure that the CD-ROM drive is the first one in the boot sequence defined in the BIOS setup.
This message may also appear if your hard disk is offline. Open the Central Processing Unit (CPU) and verify that the power to the hard disk is connected and that the flat cable is sufficiently pressed on both sides.
You may also receive this error message if necessary system files have been corrupted or removed. To find out, start the PC with a system disk or the Windows installation CD-ROM (via the Recovery Console). When you have started, type "Dir C:" to see if you can access the contents of Disk C:. If it is possible, then entering the following code will rectify the issue:
N.B. Before restoring the boot sector using the fdisk/mbr command, you should use an anti-virus under DOS as f-prot if you suspect that you may have a virus.
If none of these solutions have worked and the hard disk wasn't detected in the BIOS setup, it's possible that either your hard disk is corrupted or the partition has been damaged. If the hard disk was detected, try reinstalling or reformatting the system with the installation CD; you could also try recovering the partition using a utility.
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