There have been rolling restarts the past several days, which is nothing new. However on the morning of April 18th beginning at 5:00 a.m. PDT the realms will be restarted in order to correct a bug where items were missing from players backpacks after the previous restart.
Not every player experienced this issue. For those that did, items which were in their bags when they logged off Monday night were not there when they finally got into the game after patch 3.1 was applied Tuesday evening.
Blizzard blue poster Idrandra gives some specific instructions as to what you need to do to ensure the items are returned. More after the break.