If your vehicle is showing seatbelt won't click or latch into the buckle, here are the most likely causes and the parts you'll need to fix each one.
Small items like coins, food crumbs, or bits of paper frequently fall into the seatbelt buckle, physically blocking the latch mechanism from engaging.
The internal springs or plastic retaining clips inside the buckle can wear out or break over time, preventing the metal tongue from locking into place.
If the seats or carpets were recently removed, the buckles for adjacent seats may have been swapped or bolted in backward, causing a tongue-to-buckle mismatch.
If the vehicle was recently in a collision, the explosive pretensioner may have fired, permanently locking or recessing the buckle so it can no longer be used.