You have to ask your employer for a corrected W-2, which is Form W-2C - Corrected Wage and Tax Statement.
Make sure that your employer has your correct social security number and provides you with Form W-2C before submitting your return to the US tax office.
You must not file before you receive the corrected income documents otherwise you might receive a Notice requesting you to send additional documents proving that the filed Federal/State tax return is yours.