Most likely what has happened is one of your plugins or themes isn't compatible with the new version of WordPress. When you updated, it tried to update some sort of coding in whatever wasn't compatible and then boom, website is down.
I'm willing to bet you're probably getting a WSOD (white screen of death) and it's probably throwing a 500 error.
After doing this, when you refresh your site, you'll probably see a fatal error of some sort and it will identify where the issue is and what's causing it. After that, you can simply delete the offending plugin/theme and you should be able to see your site again. You would need to then upload a fresh copy of the plugin or theme to see if it works. If it causes the same issue again, you should contact the plugin/theme developer for assistance, talk to GoDaddy about their WP Premium Support, or speak with a developer for assistance.
Hope that helps!
I am a GoDaddy End User - Just Like You * Please note that I DO NOT answer private messages. Please ask your question in the proper forum so the answer can assist EVERYONE in the community and not just you. If you contact me via PM for help, I will give you a price quote for my personal services. Thanks! *
Once your issue is resolved, please be sure to come back and click accept for the solution