How did my phone get a custom lock I didn't put on it?

[AC Question]

my phone has a custom lock

My phone has a picture of a lock and the word custom under it. I don't know how it got there and the phone is not usable

 

[B. Diddy]

Re: my phone has a custom lock

Welcome to Android Central! Which phone? Does it look like the normal lockscreen, or is it some kind of app lock or folder lock?