Fix Network
When in doubt, Power Cycle your router and DSL/Cable box.
Apple menu -> preferences -> network -> advanced -> tcp/ip
Try the web browser - if you can reach apple.com, or google.com, you are in good shape. This means that all your equipment is working, at least partially.
Next try sending yourself an email, e.g. aol to aol.
If this works, you should be ok.
Note : if all else fails, connect to the internet through your cell phone.