Why did my S4 just randomly reboot?

[AC Question]

My S4 just randomly rebooted just as I was going to take a photo..

My S4 is working fine but as I was about to take a photo it just randomly rebooted, then when it turned on again I got this 'my documents has stopped..' something like that.. I went on to Gallery and saw a new album Camera with a few old photos I had and so now I got two albums by the name 'camera' with one showing the SD card icon on it.. It wasn't like that before and I have free space on my phone as well as on my SD card, it was weird I'm not good at tech stuff lol, so if anyone can tell me what could've happened? It's never rebooted like this. This might sound silly but at first I thought someone hacked my phone lol since it happened to a friend of mine and weird stuff started going on and she got hacked by a friend via wifi.. I have no idea how it all works but if anyone could explain it to me I'd appreciate it..
Thanks a lot

 

[B. Diddy]

Re: My S4 just randomly rebooted just as I was going to take a photo..

Welcome to Android Central! I would suspect a faulty or corrupt SD card. Unmount it (in Settings>Storage), remove it, and insert it into your computer's SD reader. Backup all of the card data to the computer, then run chkdsk. http://forums.androidcentral.com/am...guide-using-chkdsk-fix-corrupted-sd-card.html.

If chkdsk doesn't find any problems, I would still consider reformatting the card, then moving all of the data back onto it, and reinserting the card into the phone. If problems persist, you may want to try a different card.