Either there is something wrong at DarkWallet (in which case you will not be able to access your bitcoins until the developer of DarkWallet fixes the problem)
Or you have been scammed and DarkWallet has stolen your bitcoins (in which case there it nothing you can do to get the bitcoins back unless you know who operates DarkWallet).
This thread made me interested and I studied the DarkWallet website. A very shady one to say the least. Also the reviews were not good enough and even the developers were saying it is in beta status , don't try with real money unless you are willing to take the risk. I think the second option sounds more plausible to me but both options mentioned by Danny are right.
Since you are a newbie I guess it's a newbie error to not choose the right wallet. For the moment , the consensus of this forum or at least what the majority is using is this
www.electrum.org, the electrum wallet. Try it and these problems will vanish forever.