If you can't login or open a webpage, it is often because of:
an out of date browser (in this case, update your browser) or
the stored cookies and cache of your internet browser.
Open the page in an incognito window to see if is because of stored cookies and cache: if you can log in there/open the page, the problem is indeed caused by those. Delete your cookies and cache to make the page work again. Make sure you delete the cookies and cache over the entire period!
You can read more about the cache and opening an incognito window in this article.