I did this once and it drove me nuts. But Settings > Sound Settings > Phone Ringtone > (popup choice android system or select music) choose "select music" >music and then choose what song you want to play as your phone ringtone.
OHHHH! Do you have a D2G? If so, for a phone that is supposed to only have one thing different form the original, I sure am seeing a lot of differences it how they work!
Now, I vented, so lets look at what we have different. I am rooted, use launcher pro plus and the stock ROM. I use the doubleTwist app for my music player, (cause I use it to sync to iTunes.)
Settings >Sound>Phone>Phone ringtone ...I get a "complete action using" pop up that gives me choice between Android System or Select music (with the stock icon for music) I touch Select Music and get a "Select Music" pop up with the choices: Current Ringtone, System Ringtone, or Music. I choose "Music" and get a screen that says "Music - Select tract" and every song on my phone is choose-able as the ring tone. As an example the first choice I have is "Anything but Ordinary, from the album "Let Go" by Avril Lavigne (08 anything but ordinary.mp3) 4:11.
All my choices are mp3's or M4a's.
If You have D2G and do not get this same set of choices, then re-post on D2G General Issues thread and see what you get for a response form there, or Post the question on Rescue Squad Thread for ur exact model.
I see now that you have 237 posts on this forum which would indicate to me that you have the original D2. So... Why do we see different things in settings?
I'd say you should SBF back to stock and re-root and see, if you get the same pop ups I get. Or if you have D2 Bootstrapper app and saved a back up right after you rooted the phone, to reinstall that back up and see if you get what I get. If so, then add apps and changes you have made and when you no longer get the required responses, you can figure the last one is the offender.
Yes I have a regular D2 rooted running gummyjar and a blacked out theme. I went back to stock and its the same thing menu>sounds>phoneringtone>ringtones, no other option I remember my black berry had that option where it said ringtones or mp3s? But this one doesn't.
You see how after I click phoneringtone it goes straight to ringtones, so I just put my music in the ringtones folder. Or I go straight to the music player select a song and press set as ringtone but it still only plays the first 30sec of the song.
One last thing that may be messing you up. On the bottom of the last pop up "Android System or Select music" is that underneath there is a check mark you can choose to make this choice you default choice. It is similar to the pop up you get when you download a new texting app or browser, it asks you if you want your choice to be default, and if you check it you will never have the choice presented to you again.
It may be that somewhere in the past when you chose your ringtone that you made this choice even before you rooted. That is what the pictures above say to me.
There is a way to undo this but I do not know how. I have read about way back when, but did not need to use it. Maybe our moderator friends or the rescue squad know the method off the top of their heads.
Nobody ever claimed they only had one difference. The D2G is not JUST a D2 with a faster processor. It runs different software too. They're different phones, and will behave differently. Whining about it won't fix or change that.
If they were really so similar, we'd have more than 1.5 D2G ROMs available.