I bought a Verbatim 500GB external hard drive. Two weeks later I discoverd that it it does not power and by then I did not have the till sleep of the shop in which I bought it. I have so many important documents in it. How can I get it working without loosing those documents.
First, try connecting it to another PC with another USB cable. Let's rule out the easy things before getting hairy!
Second, is it USB powered or does it have a power adapter? If the latter, try to borrow one / us it in the store and see if that makes it work.
Third, we try to see if the enclosure is at fault. This requires tools, confidence, and a grounding strap. Open the enclosure, remove the hard drive, open your powered-down computer and install the hard drive. If this is your first time doing such things, look for a guide before you start, so that nothing is damaged.
If the computer sees the drive, you now have access to the data and the problem was with the enclosure. If the BIOS sees the drive but the OS doesn't, you need to get help with Data Recovery. If even the BIOS doesn't see the drive, you need someone with a lot more experience than me to help you.