No, I have lost mine before. You can try a couple of things.
Do you still work for the same person/company or can you get in touch with them? If so, you can request a replacement from them directly. It may take a couple of weeks to get to you though.
If not, look on your last pay stub and, if you worked for the same company, your W2 form from LAST year. On your previous W2, you will find the employer identification number (EIN).
Now, call the IRS at 1-800-829-1040.
Give them the EIN, The name, address (w/zip code) and telephone number of the employer and an estimate of you earnings and withholdings (which will be listed on your last/latest pay stub) and the date your employment began and ened with said company. They will pursue a new copy from their end with this information.
Your last resort if that fails is to file IRS form 4852 with your tax return. here is a link to download and fill out this form:
http://www.irs.gov/pub/irs-pdf/f4852.pdf. This is to be used IF you absolutely cannot get a replacement copy.
Hope this helps.