If I buy stock in a company and they file chapter 11 do I lose my money? How does this work? Thanks?

Common stockholders are the last to get paid off in bankruptcy. Preferred shareholders and bondholders take priority. Most of the time there is nothing left for common shareholders after everyone else gets paid off. They usually lose everything. The company then raises more money and issues more stock, which shareholders must buy again, and they start all over again.

You would be treated like any other creditor (unless it is preferred shares). You would likely lose your investment.