How are/were you connecting to the internet, via wifi or via mobile data (3G)?
On your Home Screen, you should see a bar at the top, it usually displays small icons such as signal strength, time, battery, etc. Touch and hold that bar and drag it down to the bottom of the screen.
At the bottom of this screen, you'll see Notifications and Quick Settings. Select Quick Settings and you'll see your phone's connectivity options. Make sure WiFi is On (and Mobile Network, too, if you're happy with how much you'll be charged for its use).
If you're using WiFi and your router was reset at some point, then just turn off then on the WiFi setting above.
Press the Home key on your phone to return to the Home screen.
Try the above as it's the easiest way to check things are on or to reset them if needs be. If that doesn't help, then you may need to give more information about the settings on your phone.
