Replace the belt and buckle as one unit.
My '91 Stanza has automatic shoulder restraint but I have to buckle the lap belt.
You have to replace the entire assembly.
To fix a broken backpack strap buckle, you can try replacing the buckle with a new one of the same size and type. You may need to sew or attach the new buckle securely to the strap. Alternatively, you can also try using a strong adhesive or tape to temporarily fix the buckle until you can replace it.
Best to go get a used one & replace it
To replace the driver side pushbutton seat belt buckle on a 1997 Toyota Previa, first, remove the plastic cover around the seat belt assembly by unscrewing any screws or clips. Disconnect the seat belt buckle from its mounting point by unbolting it and unplugging the electrical connector if equipped. Install the new buckle by reversing the removal steps, securing it firmly and ensuring the belt operates correctly. Finally, replace the plastic cover and test the seat belt functionality.
I don't see how you could install just the buckle. I suggest you go to almost any salvage yard and get a replacment belt/buckle assembly. Replace the whole thing.
With some belts there are clips in the reverse side, which you can use to change the buckle. What do you do if the belt you want doesn't have clips? Well I cut the stitiching or remove the rivets, depending on which the belt has, then replace the buckle and refasten it with safety pins, or if you have a thinner belt you may prefer to staple it. Hope this helps.
Check for a blown fuse first. Release the belt by pressing button at upper buckle, make sure belt to side of console is not jammed(common). Try and help motorized buckle end as you open and close the door. You should be seated in seat so the buckle does not hit you .
The parts of a belt buckle are the prong, buckle and belt.
The buckle.
"D" Rings