Did you install it yourself?
Kind of hard to answer your question properly without knowing what type of basic tip tools you use for your installs. The top of the ferrule has to be prepared again as well as the tip. If you plan on just gluing it back on without at least doing that, forget it as it will just pop off again.
Seeing that the tip has been shaped to the diameter of your ferrule, one easy way to re install is to take a sticky note and roll it around your ferrule.
Leave enuff sticky note over the top of the ferrule to be able to guide the tip back onto the top.
If you are looking to buy some tip glue that is easily accessable, I suggest trying LocTite Ultra Gel. It has a rubberized solution and will help keep the tip on a little better next time around.
PS - If you're going to use a nail and hammer to put some holes in the back of the tip, if you don't wear glasses, put on some eye protection.