How do I FORCE restart a iPhone 4s with a broken sleep/wake button AND notification area stuck midway!
So Siri can open apps, but Notification Center is still there?

I'd guess you could try connecting to iTunes, make a backup, and restore from that backup over iTunes. Or you could use iTunes to install an iOS update if you aren't on the latest software. That'd force a restart but it might be overkill. You could also try draining the battery.

If the sleep button is broken, doesn't that bother you that you have to just wait for the screen to shut when you're finished or want it off? Maybe it's time for an upgrade.