Tyffani, You are not the only one with the sound on your Nintendo 2ds not working. It may be the ribbon cable connection, internal of the device or if your volume control feels very free, the switch may not be connected to the internal mechanism. Check the attached links,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button.
http://en-americas-support.nintendo.com/app/answers/detail/a_id/616/~/faint-or-no-sound
https://www.youtube.com/watch?v=4S_Hc9vNYuE
https://www.youtube.com/watch?v=fwXzZw8IEeE