I would suggest you to try opening this link:
https://www.mymedicare.gov/ and check if it works. If it does not work, then try the steps in the following Microsoft Help article. You may face this type of issue if the webpage is not compatible.
I am having the same issue with Win 8.1 IE 11. I can not access https://www.mymedicare.gov. All I receive is "This page can't be displayed". This is the only web site
I have this problem with. I have tried compatibility mode, clearing dns cache, and resetting IE. This site works with Win 8 IE 10.