As your conversation with littleadv has indicated, the company is in the wrong; you were in fact never paid by this company in 2012, and therefore you should owe no taxes on said zero-dollar payment. The fact that you earned this money is irrelevant; revenue may be recorded when it's earned, but cash is recorded when it's paid.
You should contact the company, first. It's their books that will be out of whack as well; of course in this circumstance because your wages are an expense to them, the fact that they effectively are telling the IRS they paid you that money reduces their taxable profits. So, it will be difficult, on its face, to get the company to own up when it means a bigger tax payment to the IRS.
However, the IRS is your ace in the hole. What they are doing, if it is willful, is tax fraud; they are misrepresenting their accounting to the IRS. Big no-no. The fact that in this case they're only shorting the IRS by about $450 is immaterial; the penalties for willful tax evasion are something like $100,000 per entity charged in the crime (which is the company and anyone in the management chain who the IRS can prove knew, or should have known, about the problem), and a felony conviction with jail time for the human defendants (corporations can't serve jail time, but they can pay extra money). That's worth the IRS's law staffers' time.
So, if the company refuses to fix their mistake, you take it to the IRS. Don't think of it as selling them out, or revenge, or anything like that; you're covering your own backside, plain and simple. If the IRS doesn't know that the company never actually sent you a check, they're unlikely to dig deep enough to figure that out on your own. If, however, you simply omit this W-2 from your own tax return because it's wrong, the government receives their own copy of the W-2 and will match the records they got with the ones you sent in, and they will find the omission, and an auditor will be paying you a visit at which you will now have to prove that you indeed did not receive a paycheck from them (and proving a negative is always hard).