The OP is nearly always contacted. When this doesn't happen, the OP should contact an admin to ask what happened to their thread, as the lack of contact wasn't intentional but an accidental oversight.

The answer to why an entire thread was removed is nearly always the same -- it violated our community guidelines (usually because of back-and-forth contentious posting between a set of members). We try not to remove threads but fix them through pruning, but that isn't always possible if it would require more than the removal of a few posts in the thread.

We do not remove threads for no reason or capriciously.