The only people that can delete threads here are staff members, such as the Forum Moderators. Once deleted, they cannot be recovered. If a thread you created was deleted, there's a reason behind it, but it is highly not recommended to re-create the thread. Instead, send a private message to a moderator, and they'll be able to point you in the right direction.
If you're referring to the Guild Forum or a Group Message in the game, the answer is a simple no.