If it is on the latch I suspect it is a round head or flat head screw, not knowing what latch means. If it is a round head, you might be able to pound one of those extractors like tester has to get a grip on it. If flat head or alternative, you can drill into the center and use an extractor. They have been known to break off though making further drilling pretty difficult. If round a dremil could cut a slot or make a couple flats to grab onto with a wrench. Might even try a chisel trying to turn it enough to loosen it. Most times we try one thing after another trying to find something that work. Final try is to weld a nut on top but if you can’t use a dremil doubt you have a welder handy.
Edit: or try to get a left hand drill bit and start drilling it out.