My rear door on the passenger side is stuck so I can't open it from the outside. but today when I had the door open to ***** the problem my little brother flipped the button and turned on the child lock. now i'm unable to open the door from the inside aswell as the outside.

It sounds like the plastic connecting bit that links the outside door lever to the rod, that operates the door mechanism, has broken or become disconnected. To check, you will need to remove the trim on the inside of the door, after removing any screws and the inside door lever. However now that the child safety lock has been set it could be very difficult to get the door open.
All I can suggest is that you look at the other rear door to locate the position of the safety tab and then try to disengage it by using a suitable thin blade or something on your bad door so that you can again use the inside lever.
Once you have the inside trim off and the plastic sheet, you will see an access hole for the door mechanism and the outside operating handle of the door. It should be attached to the actuating rod by the aforementioned plastic bit. If plastic bit appears OK try re-attaching it or replacing it if broken. If the part of the handle which attaches to the rod is broken, the handle will need replacing.