Not detected hard disk
If Your hard drive is not detected in the BIOS, try the following steps:
1. Remove the hard drive from the system unit (computer off):
2. Unscrew the screws holding the cost of the hard drive (you may need a special screwdriver hex tip):
3. Clean eraser contacts, or gently scrape them with a flat head screwdriver, then clean with alcohol. Designated contacts are highlighted in red:
4. Clean brush all clogged place and collect the hard disk.
5. Try to change the train to another, or stick a ribbon cable to another connector on the motherboard.
If You have a hard drive with an IDE cable, it should check whether the jumper position determines Master and Slave. On the same cable, one device must be in the master position and the other to slave.
6. Try using a different power cable to connect to the hard drive.
7. If your hard drive when you turn on knocking, then try to change the power supply.
8. Try before you turn the computer on to put pressure on the cost of the hard disk and holding the card to turn on the computer.
9. If the hard drive is sometimes determined, and then disappears, it probably occurs overheating of the hard drive. It is treated by installation of an additional fan on the hard drive or install a fan near the hard drive.
If none of those work, try to connect a hard drive to another computer. If it is not specified, then no special service equipment to repair the hard drive will not work.