From the FAQs at www.irs.gov
I didn't get my W-2 by January 31, so I asked my employer for it, but I still don't have it. What should I do?
If you don't receive your Form W-2 (PDF) by February 15, contact the IRS for assistance at (800) 829-1040. Also, you may want to refer to Tax Topic 154, Form W-2 - What To Do if Not Received, to see the specific information the IRS will need in order to prepare Form 4852 (PDF), Substitute For Form W-2, Wage and Tax Statement, or Form 1099R, Distributions from Pensions, Annuities, Retirement or Profit-Sharing Plans, IRAs, Insurance Contracts, etc.
Yeah, I know, governmental gibberish, but the phone # should help or check the web site.