All apps seem to be gone
This seems to be some sort of faliure or glitch in your phone.

One way to fix this would be to factory reset your phone. by going to Settings &gt; Backup &amp; Reset &gt; Factory data reset.

I would believe that there is nothing wrong with the SD card, so photos &amp; music should be fine.

You can regain apps by then going to Google Play Store &gt; Swipe Left to Right &gt; My apps and install the apps back into your phone.

I hope this works.