How? When i click on it in settings it stops working
Is your phone rooted? Do you get an error message... IE Sorry Settings has stopped working or Force Close??
Yes rooted here means something different LOL..... I would guess maybe your service provider has either blocked that feature causing it to crash or it is just an error in the system.... You could try to pull the battery let it sit for about 5 minutes then put it back together and try that... If that doesn't work than you could try a factory reset... The factory reset will delete ALL of your data from the phone... So anything you want to keep I would backup..