why my question has been deleted?

I may have found the bug: if a published Q in default is moved into the Help Room and at the same time sent to Moderation, it vanishes. It's not in any space, or the moderation Q.

It's unfixable. If you follow some previous link to it, it appears as being in the Help Room Mod queue (which doesn't exist.) If you move it back into the Default space, you'd think it might pop-up in the Mod queue, but it doesn't. There's no Accept button, either (since you're not in the queue page.)

It's not as difficult for this to happen as it seems. You may have opened a Q 20 minutes ago and come back. If someone moved it during that time, your move will vanish the Q.