First, if you want to pay $100 for the part or $400 for Toyota to fix it, go ahead. Or take the plastic handle off, drill a 1/4 inch hole where the broken plastic arm comes off the plastic handle, and insert a 3" long, 1/4" thick bolt that has 1 inch of thread. Use two nuts, one on each side of the plastic handle to lock the bolt onto the handle. Use a hacksaw to cut off the bolt head. Bend the bolt upwards a bit if you need to. Reinstall the plastic handle. You just saved at least $100 and have a new latch that will never break again.
If the door latch on a 1999 Chevrolet Blazer is broken on the car frame, a new latch might have to be welded in. The old door latch will have to be cut out with a torch. If the latch is broken on the door, a new door might be cheaper than welding in a new latch.
If the plastic part is broken, it can not be repaired. New latch is about $ 50.00.
The following link has instructions, diagrams and pictures showing how to make this repair easily and inexpensively: http://www.findonefindall.com/toyota-sienna/siennareardoor.htm
Junk yard..
To fix the 300m latch, you will need to remove the inner door panel. After the door panel has been removed, then you can check the door latch components to determine what has broken and how to best repair it.
To fix a trunk latch that is stuck open, the teeth on the lock may have to be adjusted so the trunk will close. It is also possible that the cable for the trunk latch is broken. To fix the gas cap door latch may require a little bending and adjusting with a pair of pliers.
It is impossible. Buy a new one. Don't waste your time! I found a good fix @ http://www.findonefindall.com/toyota-sienna/ Please contact Toyota (phone number in your owner manual) to document this defect, the more complaints they receive, the better the chance of a recall. A more complete URL to the page referenced in the second answer is ... http://www.findonefindall.com/toyota-sienna/siennareardoor.htm I used that successfully to repair the broken rear door latch on my 2000 Toyota Sienna. ("Buy a new one" is ~$65. I made the repair with tools and screws lying around the house in about an hour's time. Repair at the dealer reportedly is ~$300.)
There are many causes to a broken horn. The best way to fix it would be to check the relay, change the fuse and change the clock spring usually located behind the airbag.
Replace the door latch.
You have to determine what the cause is first then make repairs or adjustments. If you have broken parts, try visiting your local wrecking yards for used parts.
If the trunk on a Honda Civic will not close the locking mechanism may be jammed. Be sure to remove any obstructions on inside the trunk latch. If the latch is broken replace it.
If it is the same as mine look for a door latch assembly, that's is what is wrong on mine but I don't know whether yours is broken or not.