Have the same issue on my Google nexus 7 32gb 1st gen with android 4.3 - lost auto-rotate. tried resetting in accessibility, soft and hard resets etc. nothing worked. Got the "set orientation" app from Google play and it works great... Doesn't fix whatever is messed up with the gyro, but lets me switch seamlessly from portrait to landscape. Even forces some apps that don't normally work in landscape to do so.