The Isner thread has been merged with Equal prize money debate
I'm not sure what other thread disappeared.
edit: that is an interesting suggestion. Maybe we can do this for threads where there might be some confusion regarding how the rules apply, as opposed to the obvious cases e.g. "Hey guys! Nike shoes 10% off!!!!" where I'm sure most people wouldn't need an explanation.
On the other hand, most users do ask about threads in the questions section when they're not sure why their thread disappeared. And that almost works out to be the same thing.