How do i reverse a custody order because my ex husband isn't follow the previous order and keeping my 7 year old daughter away from me.

I do not know what the custody order is, but if he is not following the current order he is in contempt of court and you need to file an action for a Rule to Show Cause.  If he is found to be "intentionally and willfully" violating a court order then he can receive  up to one year jail sentence,  fined, or ordered to do community service.  Moreover, if he is found to be in contempt there is a great chance he will be ordered to reimburse some or all of your attorney fees. If you are wanting to change the prior order then you need to file for a modification of custody and the court  must find that it is based on a substantial change of circumstance for a modification to be granted.