Okay well see if you can purchase an original power adapter from Logitech for it. That's the only other thing you can do at this point. This is a US link, not sure where you are:
http://www.amazon.com/Original-Logitech-Power-Adapter-Racing/dp/B00742YOEU
It's really tough to call though. It could be the power adapter, or it could be a bad wheel. Even if the wheel is not plugged into electricity at all, it will still be "alive" and recognized by the PC if plugged into the USB port.
And like I said, I have one (have since upgraded to Thrustmaster T300RS for PS4 racing) but had to repair it after about three years of a lot of use (several thousands of hours of use) between my PC and PS3. Good luck my friend! Hate that I can't help more.