I received a Macbook pro from my work and it didnt have a hard drive in it. I purchased a new hard drive and the mac would not recognize the drive. I read some forums and they said it could be the hard drive cable.
I found this site ifixit.com and ordered a new one. The shipping was so fast, I had it 3 days sooner than the earliest expected date. I found a guide on ifixit.com and followed the directions and it when it very easily. I started the computer up and it works great!!