Macbook Pro (10.7.5) won't read external HD - please help

Hi there,

This is my first time posting so thanks for your assistance!

Last night I was in the middle of watching a tv show on my laptop via my external hard drive (WD 3200BMV) when my friend called so I paused the show. The hard drive cable got knocked and unmounted without being ejected. This has happened before and it has rectified itself so I didn't worry. When I got off the phone and went to resume watching it wouldn't read the file. I assumed that I needed to eject the drive and start again but it wouldn't eject so I forced eject and then restarted my computer. When I plugged the drive back in it came up in Finder with the files listed, but I couldn't open any of the files. (The files are selected to read/write)

The plot thickens! I decided to see if the drive would work on my housemate's PC, which it did (I could access and open the files). I called Apple Support for some advice and the technician suggested I plug in a usb stick and other hard drives to my mac to see if they would work. My usb stick worked fine and so did my iphone, but my Seagate ext hard drive which I use for time machine would not come up.

When I go to Disk Utility the WD drive is showing (but I cannot verify or repair disk - "some information was unavailable during an internal look up) but the Seagate drive doesn't come up at all. Also, the light on the Seagate drive goes on and off when I move it slightly.

This is very confusing! The Apple Support tech said I should book an appointment at an Apple store, and also said this:

"Also, with the external hard drive, make sure to back up the data to another computer, then you can reformat the hard drive. There's likely nothing wrong with it, just the file formats were changed when it was force-edjected from the usb port."

That would make sense to me if I wasn't having an issue with the Time Machine Drive also!

Any assistance would be most appreciated. I am happy to give more information if needed. Cheers