Incorrect Show Poster

I created a page for my tvshow and uploaded the main poster, but a few hours ago, it was replaced by a random car image someone else uploaded as a poster and selected it as the primary poster for the show. 

What's the fastest way I can revert to my previous show poster? and is there anyway I can LOCK the poster so that it doesn't happen again, especially since I'm the one who created the page?

Show Page: https://www.imdb.com/title/tt41366593

Pending Contribution: https://contribute.imdb.com/contribution/260413-105539-110302