My employer put that I made a lot less than I really did on my W2 but I was paid in Cash. How do I go about fixing this problem<

He has all my Time Cards and records but he won't let me have copies.

I think he is trying to shaft me and I want to report this to the IRS but without those Time Cards I have no proof.

What should I do.

On the money you got in cash, did the employer withhold taxes?
If not, why did you tell them when you were getting paid?

Sounds like your employer is trying to avoid paying his portion of the taxes. (i.e. the matching FICA and unemployment, maybe workers' comp, that sort of thing.)

If you want to report him, go ahead. I went through this issue with someone I know a couple of years ago. Making it worse, he reported it on a 1099 and made it self-employment income, so that she would be stuck with the extra FICA herself. If you are aware of what is happening and you don't care, then I wouldn't be particular concerned. But if you care about this, report it. If the IRS is interested enough, they'll get their own proof.

You have the legal obligation to file and claim that money using Schedule C.