I can't get my phone out of Lock Mode?

One of my siblings put a passcode on my iPhone 6s and put my phone on Lock Mode. I tried to restore my iPhone 6s with iTunes, but couldn't because it's on Lock Mode and I need to put in a passcode which I don't know. Does anybody know a solution for this? Getting stressed out:/

Ask your sibling.

There are ways to get around it to get access to certain things (contact list, photos) but none that I know of for purely getting into the phone to use it normally. You'll need to get your hands on the passcode and if you can't, you might have to take it to the Apple store.