I had the same issue, here ís how I solved it:
One of two things happened. Either the directory /root was deleted; or a missing / corrupt .bashrc file in /root (.bashrc sources /etc/bashrc, which sets the prompt), you can run the following command to restore the original files (which are copied automatically when the root or any user account is created). Run this command as the user who is having problems OR define the destination path to /home/directory/user/
cp -v /etc/skel/.bash* ~/ #if logged in as user
