Could you give us some more details about the problem? Are you able to open the BIOS menu and navigate in it? If you do, please check if your hard drive is recognized. You may be facing a hard drive issue or a connectivity problem. If you are using a laptop that is under warranty, please contact the seller. If warranty has expired, open the laptop and check if the hard drive is properly connected. If the drive is visible in BIOS, try to repair Windows by booting from an installation drive.
If you are not able to open the BIOS menu, there may be a serious hardware problem and I would recommend you to contact a technician.