Problem wth SD card??

[farmgirlhlper]

I have had a Droid HD MAXX for about 2 months now. I just bought headphones to use my phone as a MP3 player like I used to use my last phone. I have been listening to music from my SD card which was installed into this phone the day I bought the phone by the guy at Verizon. Worked fine. Then I got a call while I was listening to music. I took the call, hung up from the call and then went to the- "Play music" APP only to have NONE of my music there. It gives me 3 choices now. 1- shop millions of songs, including hundreds of free tracks, 2- upload 20,000 songs to Google Play for free, or 3- to copy music from your computer to your device, use a USB cable.
There was an error message also that said my SD card has been unexpectedly removed???? I have my phone in a case and I don't even know how to take the cover off to get to the SD card!!
I just spent over $200.00 on headphones to listen to music that just disappeared. PISSED OFF!!!

If anyone can tell me how to get the freakin' cover off this phone so I can take out the SD card and reinsert, I think that would be the best place to start. If this has happened to someone else and that is not what I should do, let me know that.

Thanks!!