Also, try plugging you BlackBerry Smartphone into your computer and see if you can find the media card memory or the ringtones through media manager or Roxio in BlackBerry Desktop Manager.
This is why i asked if you had a Media Card installed. Is formatted? Some may need to be. Some can be formatted from the BB, some you must format from the PC.
If you try going into your Desktop Manager and then into the Media Manager you can find out where the ringtone actually is and if it is. If it's on the device memory then transfer it to the computer in a folder you know and then try transfering it back to the mediacard memory on the device.
Unplug the BB from the PC. Look at Options > Media Card, it is recognized.
Do this now...
At that screen, Media Card Support = ON
Encryption = None
Mass Storage Mode Support = ON
Auto enable Mass Storage Mode when connected YES.
Now, plug up the BB to the PC, and you should be able to simply use the Media Card as another removable drive on your PC. You can drag and drop files from the PC to the BB Media Card.
Anytime the BB is plugged to the PC, you won't be able to see the Media Card FROM the BB.