anacondaのjupyter notebookが起動しません。

Question

anacondaが急に起動しなくなったので、アンインストールして入れなおしたのですが起動しませんでした。また、anaconda promptでanaconda-navigatorと入力するとanacondaが起動はするものの、jypyter notebookが起動しません。どうすればよいですか？

エラー文
Traceback (most recent call last):
File "C:\Users\c0119330e4\anaconda3\Scripts\jupyter-notebook-script.py", line 6, in
from notebook.notebookapp import main
File "C:\Users\c0119330e4\anaconda3\lib\site-packages\notebook\notebookapp.py", line 49, in
from zmq.eventloop import ioloop
File "C:\Users\c0119330e4\AppData\Roaming\Python\Python37\site-packages\zmq_init_.py", line 47, in
from zmq import backend
File "C:\Users\c0119330e4\AppData\Roaming\Python\Python37\site-packages\zmq\backend_init_.py", line 40, in
reraise(*exc_info)
File "C:\Users\c0119330e4\AppData\Roaming\Python\Python37\site-packages\zmq\utils\sixcerpt.py", line 34, in reraise
raise value
File "C:\Users\c0119330e4\AppData\Roaming\Python\Python37\site-packages\zmq\backend_init_.py", line 27, in
ns = select_backend(first)
File "C:\Users\c0119330e4\AppData\Roaming\Python\Python37\site-packages\zmq\backend\select.py", line 28, in select_backend
mod = import(name, fromlist=public_api)
File "C:\Users\c0119330e4\AppData\Roaming\Python\Python37\site-packages\zmq\backend\cython_init.py", line 6, in
from . import (constants, error, message, context,
ImportError: cannot import name 'constants' from 'zmq.backend.cython' (C:\Users\c0119330e4\AppData\Roaming\Python\Python37\site-packages\zmq\backend\cython_init_.py)