Any pictures of the old hardware?

Yes! here you go….not the same room but same hardware

You can see why all the hardware needs to be replaced and the door jambs repaired and repainted….

I'd say it's unlikely you'll find an exact match for the width/thickness etc for your old strike plates. Based on your photo, it looks as though your casing isn't set far enough back from the jamb and it pushes the strike plate forward. How are your carpentry skills? Some small adjustments with a chisel/knife might be in your future :)

They won’t close or they won’t latch? I’ve had to adjust a few of these - they were either too high, low , or needed to be moved in. If the dark mark in your first picture is from the latch, it looks like the strike plate is too high. You need a utility knife, hammer, and chisel to notch out the recess a little lower than it is now.

I just did this one a few weeks ago.

Typically one needs to chisel/drill out a hole in the wood behind the hole in the striker plate.

If the hole is not deep enough, the latch will not full extend.

As said a wood chisel would be the better tool. But lacking that if you have a utility knife or maybe some drill bits you can accomplish it "good enuff."

You say it is the new strike plate's "knurled flap" (my words, don't think there is a technical term) that is longer than the one on the old strike plate. All you have to do is cut a slit inside the latch bolt mortise to accept the longer "flap." Or use some drill bits and drill a few shallow hole depths in-line. The rest of the untouched existing mortise depth should be fine to accept the new lockset latch bolt.

However, there is some stuff you should do first to make it all right:

- Measure the flat edge of the location of the lockset latch bolt: Remove the strike plate. Shut the door so it is firm against the door stops. Take a piece of paper and stick it in the door gap to measure where the latch bolt hits the jamb and mark the paper. Open the door, and transfer a line where the edge of the latch bolt inserts into the mortise. This is to make sure you put the "flap" into the mortise to allow the latch bolt to spring into the mortise and your door is firm when shut.

- In concert with above, mark the top and bottom heights of the latch bolt so your strike plate will be centered over the latch bolt. There is play here, so the existing may be fine.

- Place your new strike plate within these marks and trace the outline onto the jamb. Make sure it is straight, as right now you have it angled a little bit. The old jamb mortise (that allows the strike plate to sit flush) may be a little off for the new one, so use your utility knife to mortise (cut a depth) and allow the new strike plate to be flush.

- The old screw holes in the wood may be slightly off on your new strike plate. A few methods to fix this, depending on how far off. One way is to drill a tiny pilot hole and use a longer screw and force it to center on the new strike plate holes.

- If the latch bolt mortise needs to be bigger, or the strike plate mortise deeper, then use your knife to score the wood in a grid and "chisel" the wood out as necessary.

It's a struggle to explain with words. There is probably a Youtube video.

____________

* lockset - the door handle on the door

* latch bolt - the springy retractable part of the lockset that is angled on one side and flat on the other

* mortise - the hole in the jamb to accept the latch bolt, also the thin recess in the jamb to flush the strike plate.

* door stops - the wood perimeter that the face of the door stops against

Thank you SO MUCH for all this helpful information!!

They won’t close or they won’t latch?

Did you try to google words like youtube strike plate adjustment diy or similar? I find watching videos in these circumstances pretty helpful.