Can't turn key in 2018 international

The key is worn or ignition pins drop. Going to need a locksmith or if near a International dealer try get a new key made.

 

Yes it is safe.

 

Tap on it with a hammer, seriously, I've seen it work. You will need a new ignition switch, however. Like banging on an old sealed beam headlight, you only get a couple,,

 

No spare key to try?

 

I was sitting right on the scale at the gate during an attempted pickup at Campbells Soup in Paris Texas when the key on my Prostar did that. My truck would shut off after about 45 seconds. I had no idea that switch was about to go. It took about an hour to get a wrecker out there. Then had to sit in a hotel for almost 3 days waiting on a new switch.