The first thing I would do is check the engine oil. Next, remove the valve cover to see if any valve train components like valve springs or rocker arms are worn or broken. Here is how to remove the valve cover. Check out the images (below). Please upload pictures or videos in your response of any problems so we can see what to help you with.
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.