lb77

hi my pc has usb ports at the back and 1 at the front, my usb port at the front of the pc no longer reads it still powers up but wont acknowledge a device. (i know this because my card reader light comes on but will not show cards slots as drive g,h etc..) when i plug the card reader in usb port at back it recognise it and same with my memory stick) this problem started when i plugged in my usb convertor so i can use playstation joypad to play snes emulator. i have used this many times and never had problem. but the other day when i plugged this in i got message "new device etc... not installed correctly) since then the usb port has not been working properly (yet it can still power a device) i looked in device manager under USB bus controller no problem there. i did alittle research and turned off pc and unplugged power and this still has not fixed my problem. any suggestions?