OK,I am giving you a complete tutorial of troubleshooting SATA hard disk.
Following may be cause,why ur hard disk is not detected.
1)ur hard disk is not connected to power or the power cable is loose.
2)ur SATA disk is not properly connected to the SATA host adapter on the motherboard.
3)Damage to the signal or power cable can also cause an SATA hard disk to appear to fail. Try with another set of cables.
4)The SATA host adapter on the motherboard might be disabled in the system BIOS.Make sure you have enabled it.Below fig will help you,wht i m saying.
5)Make sure you have SATA adapter driver installed.You may have not installed drivers for an add-on SATA host adapter during Windows installation. Restart Windows, watch for the prompt to press F6 to install a third-party SCSI or RAID driver, and provide the SATA host adapter or chipset driver disk.
That all I can suggest you to troubleshoot your SATA hard disk.If none of these work for you,than few more suggestions for you.
1)Try ur hard disk in ur frnd computer,with all cables of friend computer.
2)Borrow any SATA disk from ur frnd,and try in ur system.
Now you will be able to figure out the problem.
Good luck.