I had locked myself out of my car too. But the key inside was the only one I had so I had to get a new one. I had found an article named "
Locksmiths near you," and I opened the page. I later asked them to code a new one for me. They did in a day. The only way to prevent this situation from happening again is to keep the key to yourself. And unlock the doors before opening the trunk. By that, none of this would happen. Before putting something in the trunk, I try to always open it first. You should try those.