You will need to determine whether your already filed return was 'accepted' or 'rejected'.  If it was rejected, you will be able to login to your return and fix the errors that caused the rejection, as well as the corrected W2 information, and then refile.  If your return was already 'accepted', then you will need to file an amended return.  You should not file your amended return until your first return was fully processed and/or you've received your refund or your payment for taxes owed has cleared.  

You can check your E-file status here: https://turbotax.intuit.com/tax-tools/efile-status-lookup/

You can check your return status with the IRS here: https://www.irs.gov/refunds

Amended returns have to be printed and mailed.  Please find the following helpful information about filing an amended return with TurboTax:

https://turbotax.intuit.com/tax-tips/amend-return/how-to-file-an-amended-return-with-the-irs/L6kO691...