If you have ever used the ethereum.org wallet, it's actually a horrible thing to use. If you have sent Ethereum into this wallet, it's possible your balance never shows up as the wallet seems to take an eternity to sync. So if you have this issue, you'll want to import your wallet details into another wallet which you can do this with myetherwallet.com.
Avoid ethereum.org Wallet
Ethereum.org sounds like the most legit place to get an Ethereum wallet. It is a legit wallet no doubt but there is a severe lack of support behind it and you are better off getting another wallet that has far more support for other cryptocurrencies, like exodus.io for example. For all the articles that try to help you skip downloading the entire Ethereum chain or how to access and control your Ethereum, the best way we have found is by importing your wallet into myetherwallet.com
How to important from ethereum.org into myetherwallet.com
Follow these steps to import your ethereum.org wallet. You'll need to know the password you used in creating your wallet. Once you have this, you can continue to use myetherwallet or quickly send the money to another wallet that you control.
Step 1: back up your account
If you go into the account settings you should be able to do a backup which really takes you to your folder on your computer that stores data.
So go to File >> Backup >> Accounts
Step 2: copy your keystore
Make a copy of your keystore somewhere on your computer or a USB key. You'll need this at myetherwallet.com.
Step 3: go to myetherwallet.com and import wallet
Visit https://www.myetherwallet.com/ and on the home screen on the right you'll see the text "Mist / Geth / Parity: Use your Keystore File (UTC / JSON) to access your account." Click on that to get to the next page.
Step 4: Select Keystore / JSON File and
Click on "Keystore / JSON File" and click the box to find the contents of the keystore folder. The file should start with UTC and is a JSON file. If you get stuck at this point, ask a tech friend to help you out.
Step 5: enter your password, see balance
Just enter your password after importing the JSON file and you should see your balance. You can then choose to send the ETH you have in your account and send it to another address.