I stuck a piece of paper in my trumpet so I could see what happens, I played it and it's broken, how can I get this piece of paper out of my trumpet?

Catch the paper on fire it should burn and then poof! New trumpet

Do not light the paper on fire. The heat may damage the finish. Do this: take your trumpet apart like you are going to clean it, run a cleaning snake down the other end of the tube you stuck the paper in, push (hard), the paper should become dislodged. Now, don't do that again. Good Luck.