usb device installs and works but it wont show up in my, My Computer??

I have an Amd pc chips board and when I connect certin drives I get
them all to work but some wont show up in my computer?

There is no drive letter in the device manager attached to the device
and when I give it one it still dosent show up in my computer

I dont have damon toolz

devices that have there own power supplies seem to work fine (printer,
usb, flash drive, key board, mouse, etc...

The only two that dont work are the mp3 player and my usb to card
reader for my camera.

Every thing else works

The only thing I havent tryed yet is unplugging all the usb devices and
trying them one at a time to see if its a power issue.

maby I have damaged my usb ports some how?

Im lost at what it could be im sure its not a driver issue and im
working to see if its a power issue but the hole no drive letter
allocated thing is throwing me off.

Any suggestions?