The credit card worked for me!
I tried cleaning the headphone jack and docking port, restoring my iphone, resetting all of my settings, plugging and unplugging headphones and chargers, and blowing into every ihole I could find! Very simply, this is all I had to do: I went into my music and started playing a song, took the corner of my debit card and wiggled it around in the docking port. ultimately, I think that the problem was finally fixed when I pushed up from under the post toward the screen. My volume bar came back up on the screen and everything is working perfectly now. Thanks for all your help!