External Hard Drive Not Recognized

I have been using my Iomega External Hard Drive to back up my files on my PC (HDD Model). To date, was working great. As luck would have it, my computer gave me the blue screen and said "pysical memory dump completed". So, I bought a brand new iMac. Not, I am trying to transfer my files and my Mac won't read/recognize the drive. Worse, my friend's laptop won't read/recognize. Problem with teh external hard drive? I am very sad about this as all my files are backed up there, it is my last resort. Help.