Jupyter notebook is no longer working on anaconda after tensorflow installation

I have a serious problem with Jupyter working from within of Anaconda. All worked perfectly well until I installed Keras and Tensorflow. Since that moment I receive a blank page when trying to open a Jupyter Notebook in Anaconda (opening the Firefox Browser). The browser correctly shows the directory of my work on C:/users/BFR/Python . However, when trying to open any of my ipynb - files, which work perfectly well on my other computer on which I have not yet installed TF and Keras, I just get a blank page thus not showing any code! I reinstalled all using the procedure in

… to no avail, I gave full admin access in all concerned folders - no solution to the problem… I spent hours on this problems and could not get away from the blank jupyter page in Anaconda! Please help - THANK YOU SO MUCH ( I cannot believe that am the only person who fell into this trap in the AI community ! Sincerely brordorf@gmail.com