Logan Felice

I placed colored glass down, it still shines colored, but the glass itself is black too.

Alright, nevermind. I think I got it. I tried putting sand in my inventory and a chest, then ran these tests:
1. Saved and then went right back in: Sand still there
2. Closed MC, then reopened my world: Still sand
3. Closed MC, then just logged onto my brother's 1.7.9 user, but didn't open the world: Still sand
4. Opened my world with my brother's 1.7.9 user, but didn't delete anything: Sand gone

So I think my brothers just opened my world, and its items got deleted. Is this fixable?

Also, I think that's why the difficulty kept unlocking.

@Blah We have different Minecraft online usernames, and local profiles.
@Samuel I do have a separate profile, but I didn't know you could set the different saves.
@Kumasasa I don't know when it happened, but I'll re-create the situation, and see what happens.

@Blah I'm using the same snapshot each time I play. They use their separate profiles, which are 1.7.9, but don't touch my world. Then, I go back onto MY profile, the latest snapshot, and find my stuff gone (has to be deleted, because my character hasn't moved; no evidence of greifing) and my difficulty unlocked, even though I lock it at hard.