You can contact the IRS and ask for a wage transcript, or contact your company for another copy of the W2.
Additionally, please visit How can I get a copy of my wage and tax statements (Form W-2)? for more instructions on how you can get a copy of your W-2 from the social Security Administration since your employer also submits a copy of your W-2 to SSA. However, there is a $90 fee for the replacement of your W-2.
