Whats the name of the part?

If your car has power locks sometimes you can hit the lock switch a couple times then making sure it’s in the unlocked position try shutting the door an see if that helps. If it does then you could try using some WD-40 an lube it up good. This is just a cheap inexpensive thing to try first. I’ve got an 04’ Saturn Ion an I have to do this everyday to it for the door to latch.