What can I do if my (now, past) employer is refusing to pay me for hours I worked?

I received my bi-weekly pay check a little over two weeks ago and it seemed to be off. It said I was paid for 52.75 hours, but when I went on our employee website, it confirmed my suspicions; it showed that I worked 72 hours. I printed out every pay period for the last 5 months and compared it to the hours on my paychecks. They all matched up, except the for the pay period I'm referring to. The owner gave me a new excuse and a different amount in what he felt he owed me every single day, for a week and a half. I have documentation from their website as my proof, I figured out my hours by memory, text records and looking at a calendar and my superviser oringinally told me that I worked 72 hours (and she's the one that turns our hours into the owner for payroll). I'm so glad I was proactive in printing out all my documentation because the owner sent me a hand written check for only 7 hours and some spread sheet he created and fudged the times I worked. It does not match the original documents that say he shorted me 19.25 at all, and now, all of sudden, I'm locked out of the website. He tried to tell me last week that's he's sending me this check for 7 hours and that's that.