Passport elite won't appear on my computer

I recently got a new laptop with windows 7 after my previous one with windows vista stopped working but luckily everything was backed up onto my external hard drive. But after two days, it won’t appear on my computer anymore so I can’t access any of my files at all. It was working fine for the first two days and I was able to access it and get what I needed off it. It occasionally comes up as a device but I still can’t access it and the hard drive appears to be working fine, I can hear it spinning but then it stops but the lights start flashing on the hard drive. I have tried it in another laptop with windows vista and it won’t come up on there either.

Please help; I don’t want to lose all of my files!

I have  a similar problem with my passport elite 500G. It worked well for me before, but since last month it didn’t show up on the computer. I changed several computers, it didn’t work for any of them. I could always hear the sound and feel it’s working, and only the first light was on occasionally. What is the problem?  Is it still possible to solve the problem? Please help me. The files inside are important for me. Thanks.