Installed new psu now my 500gb western digital sata hard drive wont detect in bios please help!!

Hi I bought this computer a year ago it was a custom build form a computer store. When i bought it it come with a generic 300 watt power supply. I had to install a new power supply due to the fact the video card i wanted to use would require lots more power so i installed an amd 550 watt power supply had no issues after installing it. System worked great for a year then all of a sudden the video card would go no signal and gpu fan would go 100% when it did. I did some research and found out the power supply was dying so i took the video card out and went to the onboard video. Then last night the bearing in the psu fan failed and became very loud so i shut down the system for the night It was working perfect before i did other than the rather loud psu fan. I woke up this morning and decided to put in the power supply that came with my computer the generic one back in since i was only going to use the onboard video until i could afford to buy a new power supply. When i put it back in and hooked everything up I turned it on all the fans started spinning and I got to the award bios screen memory tested ok then it went to boot off the hard drive and i get system disk failure insert system disk and hit enter so I shut the system back off turned it on and went into the bios and saw that the sata hard drive was no longer being detected in the bios but my sata dvd burner was being detected. I shut the system back down I switched the sata data cables to see if that was the issue still the same no system disk error. I have 7 sata ports on my mobo I switched from port to port with the same result until i tried them all. Now im stumped I cant get my main sata drive to detect no matter what i do. I need some help with this as my computer is my only way to watch anything due to the fact i have no cable just high speed internet I need to fix this asap Please can anyone one help me with this big issue.The power supply im currently using sat for a year unused before I put it back in.

pc specs
gigabyte H57M-usb3
4gb exelram
500 gb western digital Caviar blue
fsb group 300 watt power supply
windows 7 premium