Suddenly hard disk failure

[datis]

Hi
I had 2 maxtor 500gb sata hard disks which i have created a raid1 with them, i was working about 3 months with them but suddenly last night one of the hard disk failed to detect by motherborad ! i dont know what happened !! i just turned off the computer and day after turn it on and saw that error !
i have changed data cables and powers and ports but no chance !
what could happened to it ?
please help...

 

[MrLinux]

One of these ? http://seagate.custkb.com/seagate/crm/selfservice/search.jsp?DocId=207931

 

[datis]

mine is diamondmax 22, but in this link it says that after power on/off the data is not accessible, but my hard disk can not be detected by motherboard in bios...
is this the same ?