My two front teeth ache why?

Many possibilities: Get an exam so a proper diagnosis can be made. It could be anything from a poor bite to decay or even a tooth abscess.

Get checked!: There are so many possibilities, from infection, to trauma to a cavity. The only logical answer is to get checked by your dentist.

Several options: There may be an abscess in one or both front teeth, they may be inflamed from a grinding habit, there may be a deep cavity in either one, the gums may be inflamed or infected around the front teeth, or perhaps something else. A visit to a reputable dentist may offer more beneficial information.