Don't accuse anyone of stealing something, unless you can prove it. Otherwise people tend to get defensive and you are most likely not to get anything back from them, as nobody likes being caught stealing stuff.
What I found works best, is to announce that you are missing said item and ask the people to help you search for it. This way you don't accuse anyone of stealing, in fact you kind of imply that you might just have moved the item and forgot where you moved it to. Also, and what I find much more important, is the fact that you leave a possible thief the chance of returning the item in manner where they are not caught stealing.
Often times, these kind of announcements trigger guilt within the thief (my feeling), as they are kind of caught. Now they can get out of that situation gracefully. They have the option to either place it in some place where someone else can find it and return it to you in that way. Or they can return it themselves and claim they found it in some curious place. Which way they go doesn't matter, as you get your item back and in case someone really wanted to steal it, they can leave the whole situation gracefully (nobody likes to be known as a thief to multiple people).
In fact, no matter how much you want to know who might have stolen an item, unless you can prove that it has actually been stolen, never assume that someone stole it. Always assume that you lost it. It's completely normal to lose stuff from time to time, nobody will blame you for that. But accusing someone of theft can and will come back to you, if it turns out wrong.
This is based on my own experience, though I was on the receiving end of such a request.
