Power the phone down. Completely off (hold the power key and then choose Power Off). Then, hold down and keep held down, the Volume Down Key and then power up the phone. Keep that Volume Down key held. Once the phone comes up completely, THEN you can release the Volume Down Key. If you did it right, the bottom left corner of your screen should say SAFE MODE. This loads up the phone with NO third party apps, just the base OS running. Test out whatever you need to test out with no apps running. Then, pull down the notification shade when you're done, and you'll see a notification that says, "Safe Mode is on. Tap to turn off Safe Mode". Tap it. This will restart the phone back in Normal Mode, which will load up all your autostart apps again.