When a browser says a connection has timed out it could be a problem between your ISP and the servers DNS connection.
Or it could simply mean that the web server you're trying to connect to is down. If it's your own website that is down or seems down you can check to see if it's only you not being able to connect to it by going to downforeveryoneorjustme.com
That website will tell you if the website is down for just you or anyone else.
If it's down for everyone then you should contact your website host and see if they can fix the problem for you.
If it's someone else's website the only thing you can do is wait it out and check back later.