Was the deceased level 10 or lower? Oh dear.
People leave World of Warcraft for all kinds of reasons. Sometimes it's an impassioned ragequit, sometimes it's a 'meh, don't care', but sometimes they come back. What happens if the toon got deleted? Well, Blizzard's now letting players recover their deleted toons, as soon as Warlords of Draenor launches, but as you might expect, there's one or two conditions.
First, the deceased cannot be under level 10 or, if a Death Knight, level 55. Those poor souls have ceased to be. They are bereft of life. Pining for the fjords. Remember that little dude you left naked by the mailbox, waiting for a care package? Yep, he's gone now, and he won't be back.
Level 29 or under, sir? One hopes sir has been gone less than 90 days; if sir has been gone 91 days or more, then sir's toon is unrecoverable. Those between level 30 and 49 are recoverable so long as sir hasn't been absent for more than 120 days. Otherwise, poof!
All characters level 50 and above can be recovered at any time, so there's hope for your level 60 Warlock yet, but bear in mind that sir can only perform the Undelete ritual once every 30 days. If you have half-a-dozen alts waiting in the wings, you may have to think carefully which of them you want to bring back from the dead.
On the flip side, anyone who comes back from the Great Beyond has all their items and inventory restored too. Blizzard wants you to jump into the fun right away.
As for your toon's name, it will be kept on the record books "for a limited time" says Blizzard. However if your recovered toon has the same name as one of your current ones, then one of them will have to switch servers, change name, or be deleted.
Don't forget that, a few days ago, WoW announced the great name reclamation drive, freeing up names belonging to characters who haven't been active since November 13th, 2008. Your toon's name may already be one of the reclaimed, if you've been gone a really long time.