Internal hard drive not recognized, not even in disk utility

Hi,
I have a 2009 13 inch macbook pro with 2.4 ghz processor, 4 gb ram, all stock from apple. Machine has been working great until 2 days ago when my system froze, had to push the power off button, tried to reboot but got the flashing folder and the internal hard drive was no longer recognized. I did all the usual things and read the apple support page to no avail. I booted from the install CD and the drive is not recognized in disk utility.

I took the drive out, put it in an external case and booted from there and the drive appears to be working. I put in another internal drive, a Hitachi 500 GB/7200 RPM that looks mac compatible, disc utility will not even recognize it either with the external hard drive OS running or from the install CD. In system profiler, under hardware, it says this computer doesn't contain any ATA drives. Any thoughts?

Could this be a problem with the SATA cable internally? The rest of the logic board appears to be working as I am typing this on the affected machine running the OS from my former internal hard drive that is now in a casing.

thanks for your replies, alust2013 - good point, the s-ata did show the superdrive, but was missing the HD. kfscoll, now it is working intermittently. I think it must be a bad cable, unless I was unlucky enough to have 2 (a brand new and 1.5 year old) bad drives, which seems unlikely.

Well, I ended up buying a SATA cable for my mid-2009 macbook off ebay. It completely fixed the problem! I guess there are some bad cables in that batch.