The bar at the bottom of my screen wont show up?

So i let my little cousin use my windows hp laptop to play internet games. When i came back on it today, I opened the google chrome and the bottom taskbar disapears when iternet is in full screen but comes back if i minimize it. How do i fix this? And yes ive tried going to control panel and fixing it. Ive also tried the check box lock toolbar but its unchecked.