Use Google and select IMAGES - enter oven door hinge - look at the pictures and identify the ones you have - some of the images show how the locking mechanism works.
Use youTube and look for videos about oven doors.
Remove the door and check that each hinge sits at the same angle - if different remove the hinges and rectify - sometimes the frame of the hinge becomes distorted.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix electric cookers.