I worked part time for a corporate company that never paid me. I received a W-2. Who do I contact? I tried to reach the manager but he won't return my calls.
If they didn't pay you, you do not owe any tax on the W-2 income, but the IRS will be informed of the income and expect to see it on your return.
You should contact the company asap and tell them that as they didn't pay you, their filing of Form W-2 was incorrect and ask them to correct and issue you a W-2C. They probably won't want to as it's a real pain depending on how big the Company is, but if they do, that would solve the issue.
Even if they don't, as long as you have proof that you were not paid, you are not subject to any liability with the IRS with respect to this matter as long as you can document that you never received anything from them. You would probably get a letter from the IRS asking why the income was not reported by you and you would then send them the evidence of your not having received it and that would be that.
I tried to reach the manager but he won't return my calls.
If this is a corporation, call their Human Resources (HR) department. Or their payroll department. Your manager probably has little to do with payroll. This also takes some emotion out of it if you and your manager parted on bad terms.
Consider the possibility that they cut you a check that you never received. It might be easier to get them to send you that check or a replacement than to to get the W-2 changed. If so, try to resolve that quickly. That route probably involves you paying the taxes as if you were paid last year.
If there are difficulties, there are additional steps that you can take. But they depend somewhat on the circumstances of you not getting paid. Some of them might fit better on Law.SE or Workplace.SE -- we're getting into a gray area. My main point was that if you're dealing with someone large enough to have an HR department, that's where I'd probably start regarding this. They can tell you the way that things seem from their perspective.