If you've exhausted all efforts to track down a W-2 from your employer, you can file Form 4852 Substitute for Form W-2, Wage and Tax Statement. In this case, you will need to print a hard copy of your return, attach Form 4852, and mail it to the IRS.
To substitute Form W-2:
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.