3DS Disappearing Characters

[Find's Lazy Jigglypuff]

I was recently playing Terraria on my 3DS just now, and I closed the 3DS to let it go to sleep for a little bit. I came back about 15 min later to open my 3DS and it tells me that the save did not succeed due to the SD Card being locked (?). Next thing I know is that the music is on a repetitive loop, but was still able to play the game. Although, I was afraid that something might happen to the game so I booted back to the home screen. When I started it back the 3DS couldn't start Terraria, and I restarted the whole system to reopen the game again. It works fine but the character I used disappeared along with my entire inventory. The world I was playing on is still fine, so I dunno what the major problem is right now or how to fix it.

 

[Nitpicky]

I haven't played Terraria on any consoles, but if it works like the computer version, it's because Terraria often makes save of your character and world while you're playing. And if it works like that, it means that you've closed your 3ds at the wrong moment {because when you do that, the 3ds apply a "new mode" so the connection to the sd may be disrupted, even a little second} and corrupted the save of your character. If it's that, there's maybe no way to get it back.