I had the same problem with the Settings Menu when I disabled the Lockscreen in Android – I could not get back into the Security Menu (I think this is a bug). I found this work around to get back into the Security Menu: Go to Settings – Under “Wireless & Networks” select “More…” – Select VPN. You will then be prompted to set a lock screen Password or PIN – Select OK. Next Choose whatever method you like “Pattern”, “PIN” or “Password” – make sure you remember what security Pattern/PIN or Password you enter . You can then exit the VPN menu and get back into the Security Menu using whatever Pattern/PIN/Password you set up. You can now select a different Security option (such as “Slide”) as long as it is NOT “NONE” otherwise you will have the same trouble getting back into the Security menu
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