If you're talking about the Lee Universal Decapping that looks like the pic below, look and see if the pin is sticking out of the top. If it is, it just slipped like it is supposed to when it encounters too much resistance. If so just loosen that nut on the top, move the pin back down where it is supposed to be and tighten very firmly.

If you get the pin out and it is broken here's a link to buy a new one for $2.49. I think they have two different styles of pins, changed designs a couple of years back so make sure it's the right one. I've only ever broken one and that was because I hit a rock that was stuck inside a case. Many other rocks it's smashed through without issue.
New Pin $2.49