You should go to the Get A Transcript webpage at the IRS.
You should look for the "Wage and Income Transcript" - this will have copies of copies of documents like W-2s that companies sent to the IRS, for up to the last ten years.
You may be able to get the transcripts online if you can satisfy the IRS as to your identity; otherwise mail in form 4506.
NOTE: a transcript is a line-data rendering of the data; it contains the numbers, not lines and boxes and shading. However, it is generally all you need to file, and even better, it's free!