Portable Hard Drive (Iomega) Problem

I have a portable Iomega Hard Drive ( S/N : YSDA100331 & Model : RPHD-TG)Since I started using the hard drive, I've connected it to my computer using the USB cable that came with the device - this has worked perfectly and I've never had problems before with power supply ect. However, I went to use the device today & the computer won't pick it up (doesn't appear in my computer at all) - the light that signals if the device is on comes on solidly (meaning I assume there is enough power) but the device doesn't actually do anything - usually it made a noise when it was on. It also makes a beeping noise for a few seconds. I've tried using different ports, different cables, restarting my computer, looking for updates. Nothing seems to work. Does anyone know how to solve this?