Start with clearing your browser cache and try logging in again. 

Google Chrome: Hold shift and F5 at the same time

Firefox: Hold ctrl and  F5 at the same time

Safari: Hold shift and click the refresh button Or Command + R

Microsoft Edge: Click on the menu button situated in the upper right corner. Under Clear browsing data, click on Choose what to clear. Check the boxes next to Cookies and saved website data and Cached data and files.