How to unclog a toilet? (solid object obstruction)
As the comments suggested, first try and grab it with your hands.  If it's passed the point you can reach, you will likely need to use a Toilet Auger to dislodge it.


(source: homedepot.ca)  

Tooth brushes tend to be problematic because of their shape relative to the trap in the toilet - they can really get wedged in there!  Worst case scenario it might not be removable.