If I haven't paid my taxes in 3 years, and don't have the papers to do it, can I still get it done?

I haven't paid my taxes in 3 years. I don't have most of my W2's anymore. Can I still get my taxes done? Can the preparer( H&R Block, ect...) look the W2's up? What about penalties and fees? I want to file, but don't want to get in trouble. What should I do?