After Feb 15th you can contact the IRS and they will help you, please see the IRS website excerpt below for more info:
Missing Your Form W-2?
You should receive a Form W-2, Wage and Tax Statement, from each of your employers for use in preparing your federal tax
return. Employers must furnish this record of 2005 earnings and withheld taxes no later than January 31, 2006 (if mailed, allow a few days for delivery).
If you do not receive your Form W-2, contact your employer to find out if and when the W-2 was mailed. If it was mailed, it may have been returned to your employer because of an incorrect address. After contacting your employer, allow a reasonable amount of time for your employer to resend or to issue the W-2.
If you still do not receive your W-2 by February 15th, contact the IRS for assistance at 1-800-829-1040. When you call, have the following information handy:
• The employer's name and complete address, including zip code, the employer’s identification number (if known), and telephone number,
• Your name and address, including zip code, Social Security number, and telephone number; and
• An estimate of the wages you earned, the federal income tax
withheld, and the dates you began and ended employment.
If you misplaced your W-2, contact your employer. Your employer can replace the lost form with a “reissued statement.” Be aware that your employer is allowed to charge you a fee for providing you with a new W-2.
You still must file your tax return on time even if you do not receive your Form W-2. If you cannot get a W-2 by the tax-filing deadline, you may use Form 4852, Substitute for Form W-2, Wage and Tax Statement, but it will delay any refund due while the information is verified.
If you receive a corrected W-2 after your return is filed and the information it contains does not match the income or withheld tax that you reported on your return, you must file an amended return
on Form 1040X, Amended U.S. Individual Income Tax Return.
Forms 4852 and 1040X and their instructions are available on the IRS Web site, IRS.gov or by calling 1-800-TAX-FORM (1-800-829-3676).