If someone filed a tax return and used your social security number and/or your dependent's, you will still get any refund to which you are entitled.  However, it will be delayed.  Also, you won't be able to e-file your return - you will have to print and mail it.  Since it sounds like you are a victim of Tax Identity Theft, please see the following TurboTax Help article for what you should do next:

What to do if you suspect tax-related identity theft