First of all: calm down, you cannot just lose funds of an identity. The blockchain does not work this way.
Either you have sent all your funds to another address or they are still on your wallet.
Most of the time if you think you lost the funds of your identity you are simply connected to a different blockchain.
If you have Ether for the main chain (Homestead), you need to be connected to it. Simply change the network in the menu like shown below.
If your funds still do not show, wait a few seconds until the app has synchronized.
In case your funds still won't show you need to check your address for any unusual activity, you can do this by searching for your address on etherscan.io.
If you notice any unknown transaction it is possible that someone gained access to your private key and sent your funds to his own identity.
So please make sure that you backup your private key at a safe place and that only you have access to it!