What do i do when my computer shows the message non system disk or disk error

SOURCE: Non-system disk or disk error

hi there,
please make sure that there is no USB flashdrive or any other USB device connected to the computer.
If that's cleared and the same error happens please try to reseat the hard drive because chances are it is not detected by your computer. (you would have to unscrew a small cover from the back of the laptop and take the hard drive off and put it back in)
If that does not work try going to the BIOS and check if the computer detects the hard drive if not and you've already reseated the hard drive then it means that your hard drive has gone bad and it needs to be replaced.
If it detects the hard drive then try booting from a windows cd If you're using windows 7 or Vista go to Windows Recovery Environment or if you're using XP go to the recovery console.
Once you're on the command prompt issue a chkdsk /r or fixmbr command.
If that still does not work, you might have to reinstall Windows on your computer.
Hope this helps!