1. What tutorial did you follow to "restore" your 3DS?
2. What do you mean, when you say that the update "gave you a black screen"? (While downloading? After downloaded, while rebooting?)
3. You said "the guy in the tutorial said none of my games/files would be deleted". You cannot trust what everybody says. (Not saying that they ARE deleted, just making a point).
My guess would be that you "restored" your console by removing CFW and finally got it to start on 11.3. Now nothing's showing up because all your games were pirated. I don't think you can hack an 11.3 console yet. At least, it's not showing up in 3ds.guide. Back up your entire sd card, and keep it for a while. If you can hack that console again, your games should show back up once it's running CFW again.