Following these steps should help to fix any problems you are experiencing in the first instance: 

• Check that you have installed the latest version of your internet browser.

• Empty your browser cache and reload the page (F5 or CTRL+R). Generally you can do this by going to the settings menu in your browser (look for "delete history" or "delete browser data" and then chose the cache).

If you are still having problems, perhaps also try using a different browser to play the game, e.g. Chrome, Firefox, Opera etc.