Wait you had this stuff in a chest in your home and it went missing? Ariel's Bow was lost to? Man that svcks. You know some rooms in your home are for you Housecarl so maybe (?) try seeing if they took it.
No it was in fort Dawnguard.
And I I figured after I have finished the quest and saved the world from vampire overlords that no one would F with my poop at dawnguard, it really grinds my gears.
The only solution I found to this matter is simple... don't play the game for like a month or so till I'm done being pissed off, and continue from the save in which I still have everything!
I don't see a better solution