One way to try if you want to avoid rebooting is open your app tray (if you can), go to Settings -> Applications -> Manage Applications. Use the Menu button to Filter by "Running", find the Home screen app, and force close it.
Someone mentioned they got theirs back by just opening the keyboard. That's helped me when the screen won't come back on after a call.
Someone mentioned they got theirs back by just opening the keyboard. That's helped me when the screen won't come back on after a call.