Um, have you tried having your hero talk to them?,
because only your hero can accept and complete quests from the NPC's with a "!" or a "?" above their heads, if that doesn't work, then i suggest trying the usual methods, validating (If using steam), Re-installing (Both) or simply by logging out then in. If that doesn't work then you might have a bug/glitch and you would need to talk to a GM in game or wait for the Tech support to respond to your thread.