You can correct your return if you have forgotten to include a Form W-2. You will need to file an amended return, Form 1040X. However, it is advised that you wait until your refund is received, so the Internal Revenue Service (IRS) won't construe it as a duplicate return.
TurboTax supports the filing of amended returns. However, you will have to mail the return because the IRS does not allow the electronic filing of a corrected return. Your state return will also have to be amended. Please ensure that all your information is available before making the necessary changes.