We’re sorry to hear that you’re having issues replacing your toothbrush head on your brush. In the package, there will be a Quick Release Tool that is used to remove the brush head. There should be a small indent on the brush handle that it will insert into that will release the brush head. We’d be happy to help you further with this if you give us a call at (800) 566-7252 so we can. We look forward to helping you get back to brushing with ease!