Generally, as long as you have not rewritten the original data, you can also recover your deleted files from this SD card.
At first, take off your memory card from your digital camera or smartphone and connect it to your computer or laptop via a card Reader.
And then download a free SD card recovery tool
to retrieve your deleted data from http://blog4mark.blogspot.com/2012/12/sd-card-recovery.html
This freeware is capable to recover data from all types of memory card and also has helped many people restore their photos, videos, songs and files back.
From now on, you should learn to back up everything important on different storage device all the time.