If the SSN is wrong on your W-2, you will want to contact your employer and have them update the information that they have for you on file.
This is the SSN that they are using to report your Social Security and Medicare contributions, so you will want to make sure it is correct not only for your taxes but for those contributions as well.
They should then issue you a corrected W-2 (W-2C) that you can use in place of your old W-2.