Lafinass is right, before you waste any more time or money, you need to find out if the drive even shows up in Device Manager. If it doesn't, then try your new cable. He's also right in that one of the last things that would go wrong is the ribbon cable. If the new cable doesn't work, you're hosed.
If the drive does show up in Device Manager, it's likely that windows hasn't assigned it a drive letter and you'll need to do that in Disk Management. This could be because of many different things, but there are 2 most common scenarios. 1: Windows hasn't assigned a drive letter, or it's been assigned a conflicting drive letter. Or 2: The drive isn't reporting that it's formatted.
Right-click the My Computer icon, go to manage. In the tree view on the left side, click on Disk Management. Over towards the bottom right, you'll need to look for any disk that doesn't show up in the list in the upper right. If you do find one that shows in the lower but not upper, right-click it and select Change Drive Letter and assign it to a letter that's not being used.
If the lists are the same.... you're likely hosed.
If you find a disk that is showing as unformatted with ~500GB capacity, you might want to see about finding someone locally to help see if they can recover the data before you reformat.