Don't be too worried about it. There is a way to recover your pictures and music. But first of all please don't save any files to card before you get your files back.
Then you need to rely on some recovery tools. A popular one is Asoftech Recovery. This program is quite skillful to get back deleted files due to accidental deletion or formatting without technical skills. Here is the steps you may find helpful:
1. Download this program here, http://www.asoftech.com/apr/
Install the application on your computer. Then connect your card to your computer. as usual under My Computer the drive letter assigned to the external drive(usually Drive G: or Drive H:).
2. Start Asoftech Photo Recovery, then click on settings on top right part of the program, check all and click OK.
3. Select the drive letter that assigned to your card, click "Start". Now the scanning process will start automatically to find your deleted files. After a while you will get a lot of recoverable files.
3. Preview the found pictures to see if your deleted ones are there. If they are, select the pictures you want and perform full recovery to get all them back.