I created a couple ringtones from Myxer.com, and then a couple of days later they disappeared. Possibly coincided with an update (noticed my Gallery change and Goggles showed up).
Also, unless my memory is failing more rapidly than I thought, I believe I had assigned a couple of songs as ringtones, but that is no longer the case and I can't seem to find them under "Options" in Contacts.
Thanks for the help,
I had this problem many times when I downloaded ringtones from soundboards. Id set them as ringtones, then all of a sudden theyd no longer work. I went through my ringtones so I could just check it off again but it wasnt even in my ringtones. I have no clue whats going on there, but I think its similar to your problem.
However, if its from the internet you may want to sync your phone up to your computer and check your Downloads folder. From there, create the Media folder with a Notification folder inside it. Drag and drop it there and that should remedy the problem. Hopefully.
I just had this start after the 2.1 update, they dont show up in the available list of ringtones, but still show up in the proper folder on my SD card....restarting my phone fixes it but pretty annoying when certain contacts ringtones just disappear so all I get is a vibration when they call.
You know whats funnier? That almost happened to me. I set up a ringtone for a friend, then she calls. Its my Default ringtone. This makes no sense, I check out what ringtone I have her listed as and sure enough, I gave her a different ringtone. She calls back and the one I gave her rings, not the Default. I have no clue how that happened.