Booting error n no hard drive found

Hello,
i was trying to installwin xp pro sp2 ..durin installation process blue screen appeared saying some "stop*00000..."error...after i rebooted my comp i was unable to install win again...n now its displaying a msg dat hard disk drive is not found...wat should i doo/?????..n when i m restating my comp an error appears "boot failure insert boot drive in A:"...watz dat???wat can i do to install windows???have i lost my hard disk???if yes then how can i have it bak???...plzz help me summ1..:(