i pressed a button on my keybord and the web page filled the screen, when i moved the mouse to the top of the screen the address bar came back. but i cant figure out what button i pressed can any one help me

i pressed a button by acident and the page i was on maximized to the whole screen,all the bars disapeard top of the page and at the bottom, when i moved the mouse to the top of the page th the address/ back and forward buttons bar came back. i saw the red cross and minimise button top right i pressed the minimise button and now i cant find how to get it go to a full page.