do you mean you cant see the numbers,may be bulb gone? total guess as no make/model/year/type etc given,
guessing
April 2013
No one can help you fix it, you wanna know why, you failed to give enough info, like many people who visit this site. We're here to help, but we are not mind readers.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix vans.