Well what I can suggest you is to do the following
- Open the Contacts on your phone
- Choose a Contact that you want to attempt
- Press Menu. Do not choose Edit instead select Options in its place.
- Make your Ringtone choice there.
There are software available in the Market for make ringtones, or you can download a few. You be able to put them on your microSD card.
I consider you can put them in one of these folders and the OS will find it and list them in the list of ringtones from which you can make a choice . start here
Code:
sdcard/media/audio/ringtones
sdcard/audio/ringtones
sdcard/ringtones
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