* Power window switch malfunction: The master switch or the rear window switch itself might be faulty.
* Fuse: Check your vehicle's fuse box for a blown fuse related to the power windows.
* Wiring: A short or broken wire in the system could interrupt power.
* Window motor/regulator: The motor or the mechanism that moves the window could be broken.
To troubleshoot, you should start by checking the fuses first, then examining the switches. If those check out okay, you'll likely need a mechanic or professional auto electrician to diagnose the problem further. There's no single "lockout" to engage or disengage.