If the playlist was accidently deleted there is still a way to get it back so don't worry! On the spotify website go to "Account" (just click on your name right up at the top), then press "Recover Playlists" and your playlist should appear there. If it does not appear there then you may need to try logging out then logging back in on the mobile app or re-installing the app. You can always contact spotify support by going to the About section on the spotify website. Best of luck!