Macbook Pro - Not picking up Hard Drive I had a problem when I turned on my Macbook Pro, I would just get a flashing "?" when I booted up. 

I decided to grab a recovery from another mac I have, I put this onto a memory stick and my laptop went into recovery mode etc.. I then went into Disk Utility only to find out that it wasn't actually recognising my hard drive..

I then tried another hard drive from another macbook and it wasn't picking up that hard drive either. 

NOTE: I placed a CD a few weeks ago and it didn't like it, caused the fan to go crazy and I had to remove the CD through a command in terminal.

I tried cleaning the wire that runs from the Macbook to the hard drive and this picked up the hard drive at boot-up but then when I restarted, it went back to the same old flashing "?" mark. 

Could it therefore be the wire that is running from the hard drive to the main-board? If so, would this be expensive to fix (From Apple directly) or would it be cheaper for me to purchase online and fit it myself?
Based on the fact that another known-good drive did not work, it sounds like questioning the cable is the next logical step. You could confirm what you already know by installing your hard drive in your friend's computer and booting it, thus proving the Partition Table/Master Boot Record/Apple Partition Map are in working order.

It sounds like plenty of other people are having problems with their hard drive cables too. 

You can always buy an enclosure for your drive and attempt to boot from USB, ultimately proving that there is nothing else it could be. It's a tad cheaper than the replacement part.

Good luck.