If it is less than a year old you are still under warranty. Call the company and they have to send a tech to fix free of charge.
If older than a year, then you can fix it yourself if you feel comfortable. You should only need a screwdriver.
You will need to replace the button overlay (if possible) or the entire console itself.
You will need your full model number to look up parts for the machine. It is located down by the floor on the frame of the machine. Usually a white or silver sticker about the size of a credit card.
Once you have that you can look up the parts. www.fitnessrepairparts.com or www.treadmilldoctor.com
Model number should be PFTL then a bunch of numbers