Hopefully you wrapped up any prior business you had on Diablo III's auction house prior to today. As Blizzard previously announced, both the real-money and gold auction houses have been shut down and are no longer available. Any items that were on the auction houses when they were removed will be sent to the winning bidder or seller and can be claimed by June 24th, 2014.
Q. What will happen to my current auctions when the gold and real-money auction houses are shut down?
All active auctions will expire as normal following the shutdown of the gold and real-money auction houses on Tuesday, March 18. Once the shutdown is complete, items will either be delivered to the current highest bidder or returned to the seller, appearing in each player's Completed tab. Unclaimed gold will also appear in the Completed tab. Players will be able to claim gold and items and from this tab until June 24, 2014.
Successful transactions involving Battle.net Balance and/or PayPal will be processed normally and all usual fees will apply.
Source: Diablo III Auction House Closure