Sooo, I'm not the brightest person and the 3DS gave me my first SD card, when I first when to put stuff onto my computer from my SD card I formatted everything not knowing what that meant... So yea it deleted everything. Anywaysss the problem now is I am trying to put music onto my 3DS. So I took the SD card and put it into my computer and click "Open files and view them" then I took all my music and put it in a folder on the SD card called "Music" after that I took the SD card and put it back in my 3DS. Yet there is nothing changed about my 3DS/SD/Music. Why isn't the music going onto 3DS sound at all and how can I fix this? Thanks.

there's a couple things that could've gone wrong here:

• this 'music' folder, is it inside the 'Nintendo 3DS' folder on the SD card? If so, your 3DS won't be able to read any music in the folder. Move the Music folder out into the top level of your SD card's directory.
• are the music files the right type? the 3DS requires the file extensions be either .mp3, .m4a, .mp4, or .3gp. If your music files have a different extension (.ogg or .wav, for example), you'll need to convert them to one of those the 3DS will read.
• this Music folder, to get to it on your SD card, do you have to open eight or more other folders? The 3DS can't read music in folders more than eight deep.

The music folder is not in any other folder, it's right next to the DCIM and the Nintendo 3DS folders. And Idk how to check the music type. Also in 3DS sound anything that use to be under "Record and Edit sounds" is now gone. Such as "Auto Play" and others, does this matter? The music folder is just 1 folder with a lot of music in it, it's not 8 deep.

To check the music type, on your computer right click on a song and click properties in the dropdown box. Look for "Type of File: ____________" in the window that opens. If they are showing that they are MP3 or AAC, then your 3DS should be able to play them.

You mentioning that other things were there before, has me wondering about your card's condition though. I have an SD card that is corrupted, yet my photo printer can still read the images off of the card. Nothing else can do anything with it however. I am wondering if something similar may be happening with your SD card. If you can, try putting the card in a device other than your 3DS or computer, and see if you can access anything on it. For instance, if you have pictures saved to your card and you have a Wii, try to view photos off of the card using the Wii.

Everything else is working fine and I can view photos and stuff from other devices, only thing missing is anything in 3DS sound that was below record and edit sounds, that got deleted when I formatted my SD card by mistake. I'm wondering if I have to somehow get that stuff back. The type of file says (.wma). What does that mean?

wma is Windows Media Audio. Your going to need to convert your files to either AAC or MP3. I know iTunes can convert files to AAC (it may do MP3 as well, I can't remember). The solution to your problem may be as simple (though admittedly tedious) as converting your files.

EDIT: I forgot to mention that AAC files will show up as MPEG-4 audio layer file (.m4a) in the properties window.

I only put my music in one folder on the SD card and the 3DS reads them just fine

Just learned something new about the 3DS player: it will only recognize 100 tracks in a single folder. If you have more than that, it simply ignores them.

Okay, when my friend comes over he'll help me convert them. Thanks guys. Also I have like 200 tracks in 1 folder, should I make another music folder for half of them?

From what I learned today, you'll have to in order to play all of the tracks. I had one folder with 160-ish songs in it, but the 3DS would only display 100 of them. Hope it goes well for you.

is your music in DCIM i got my in that folder

and here's a video if it can help you
http://www.youtube.com/watch?v=JnjTF2Uqf78

It's called:
1. Get a SD card that works w/ your 3DS
2. Does your computer's SD card reader & writer work (my living room computer has trouble writing stuff)
3. Make a new folder in Windows Explorer (not that half-decent Internet Explorer 9)
4. Copy AAC music files to it (iTunes uses it, just make sure it's not copy protected, that won't work)
5. Pop it in your 3DS.
6. Viola! It should work.
Update:
P.S. Never use the 3DS or DCIM folders (not sure on DCIM, better safe than sorry). Instructions w/ Windows 7 in mind. If you use 7 like me, there should be a bar telling you the file type. mp3 and mp4 files work too.

Okay thanks guys.