iPhone 4 won't Charge or connect to iTunes.

Okay so it all started about two weeks ago. I tried plugging in my iPhone into my computer (it worked the day before) and I kept getting this error " Unrecognized USB" It would later say that the USB didn't install correctly. So after searching for hours online. I tried resetting all the USB hub things. I Scanned new hardware all that jazz.. Nothing worked. Well when I tried plugging in my iPhone into the wall. It didn't charge at all. So I tried the Reset ( Hold down the power and the home until it turns off. ) That didn't work. So I read online, I got all the lent and small dust particles out of the charging little slot thing. That didn't work. I tried resetting it by connecting it to iTunes and restoring it. But Once again my computer doesn't detect my phone for some reason. I have literally tried everything and nothing works. But I noticed that when ever I turn off my phone and connect it to the charger. It will charge very slowly. Super slowly like every 3 hours it would probably get 100% battery. But when I try to turn it on it goes right back to not charging.. Help please