What if your iPhone Home button and the sleep/power button stopped working?
There are a few solutions!
If your iPhone is not jailbroken, you can use the Assistive Touch option to simulate the Home Button and the Sleep button. To turn on, go to Settings->General->Accessibility->Assistive Touch.
But when your iPhone is locked, to wake up from sleep mode you can connect it to the charger. And also toggle the silence tab above the volume buttons. NOTE: You have to keep the vibration off. Go to Settings->Sounds and disable vibration.
The best option is to Jailbreak the iPhone. There is a tweak called Activator that can assign certain gestures or clicks that replace the home button and the power button. To lock the device there are also a few tweaks like QuickLock or SpotLock.
To wake up from sleep mode with Activator you can assign volumen up/down buttons as power button. The problem is iPhone goes to sleep mode after a few minutes after being locked and Activator stops to work. To overcome that, there are tweaks like KeepAwake or Insomnia that allows Activator to continue working even in sleep mode. Drains batery, but works!