Install window 7 again and make partition 1 st of all format then make partition then install window 7 then your problem will solve
You did not read the post, he is trying to install XP not Win 7, and it's not detecting a disk which makes it hard to install an operating system.
Try reseating the hard drive, then go into the BIOS and make sure it is showing up in there. Set the disk mode for the disk to "ATA" or "Legacy" if it's set to AHCI. Try XP setup again.