How to open Navigation Drawer with no actionbar, open with just a button

It's giving you a null pointer because you are trying to find the drawer layout in the fragment's view, when it is actually in the activities view.

A quick hack to do what you want is to find the view like:

getActivity().findViewById(R.id.drawer_layout)

That should work. A better way is to have a method on the activity for opening the drawer

public void openDrawer(){
    mDrawerLayout.openDrawer(mDrawerLayout);
}

In the activity onCreate run your findViewById:

mDrawerLayout = (DrawerLayout) getView().findViewById(R.id.drawer_layout);

mDrawerLayout should be a member variable of your activity.

Then in your fragment you can call:

//cast activity to MyActivity so compiler doesn't complain
((MyActivity)getActivity()).openDrawer();

An even better way to do it is to create a listener in the fragment and set the activity as a listener to the fragment. Then you can call a method on the activity, similar to above. I'll let you do some research on how to do that.

drawerLayout.openDrawer(Gravity.START);