Hi Dan,
Perhaps you should start with reading this
Problems with SimpleTech eHow It may not be of much help.
In what way doesn't it 'respond to your computer' ? Presumably you are using an MS Windows O/S, not an Apple ? You don't say. Presumably it is not showing up in Windows File Explorer/File Manager ? Again you don't say. Try using another (different) USB port(socket) on your computer. Try using the disk on another computer to tell you whether it's the disk or your PC.
Assuming it's your PC, and that hasn't worked, enter the DiskManagement utility. You should see your system disk (boot disk) and possibly the external disk as well. Right click on the SimpleDrive disk, and select 'Delete Partition' if appropriate, else go straight to 'new Partition'. I am going to tell you to reformat your disk. You will lose any data that it contains (now is a good time to remind you to ALWAYS keep BACK-UPs of your data). DO NOT REFORMAT YOUR SYSTEM DISK. Select ' New Partition' if you want to proceed with this operation, and follow the instructions, selecting the appropriate letter to assign to the disk. After about 1hr assuming USB 2, it will finish. The disk should now be visible in File Explorer.
You might also try, ensuring you have only this disk connected to your PC on the USB system (I'm assuming that is how you're connecting the disk to your computer, you don't say), entering DeviceManager, and going to USB Devices, expanding that entry. Now double click on the entry which says 'Mass Storage', and click the button which says 'Uninstall Drivers' (you may have to click the drivers tab to see this button). It will ask you if you are sure, click yes. After it has done this, disconnect the drive and reboot your computer. Now plug your drive into your PC by the USB port again; hopefully it say towards the bottom right ;new hardware found', 'installing drivers for your new hardware', and finally 'your new hardware is installed and ready to use'.
10.April.2014