The quickest way to obtain a copy of a prior year Form W-2 is through your employer. The IRS can provide W-2 information for up to 10 years. Information for the current year is generally not available until the year after it is filed with the IRS.
If you do not have a copy of your tax return from last year, you could contact the IRS at 1-800-829-1040 and ask if they can provide you with the information needed. You can also contact your tax service for a Copy of Tax Information.