Trunk won't latch to lock? What could be the problem?

Joann, 1 st check the latch assy. for any visible damage, replace if bent or worn. Sounds like the lock mechanism is seizing up, You can try to spray with a thin oil WD (penetrent oil) etc. to free up including inside lock, to lube the small tumblers inside. You have to, if able, remove latch assembly and soak in oil over night if real bad.
The lock actuator may also be defective and links below will tell more about that.
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."

Trunk will not Latch Auto Repair TalkLocal Blog

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BROKEN LATCH!!!!!REPLACE IT AND EVERYTHING WILL BE OK!!!!COMMON PROBLEM!!!!!!

So you know how to work the latch, and the latch is working.

Now you need to look and the holding bar, if you have to remover the plastic cover to see how it's bolted on do it.

Sounds like the bar moved down so the trunk hits the gasket before it can lock on the bar.

See if loosening the bar bolts will allow the bar to be raised just a hair.

Take the latch apart to see the problem. This is a power lock?

The latch is most likely the issue. If the trunk is used a lot, the latch is misaligned or a foreign object obstructed the latch from closing. The latch itself could be damaged. Carefully inspect the opening of the latch and look for bent, mushroomed or damaged steel. I would have to see to know for sure, how to proceed.

when jump starting volvos turn the lights on this will stop the power surge from blowing fuses or relays that have stopped all your bits from working

check the latch and striker, it may be out of adjustment or bad. the part where trunk latch locks onto. good-day !!

1. Open trunk
2. Place latch in lock position
3. Pull inside trunk release to see what isn't moving
4. If trunk key won't turn, the key may be worn out and need to be replaced

Any repair shop (body shop or auto repair shop) should be able to handle trunk repair. You may want to look through your local yellow pages. Have you tried spraying a lubricant into the latch assembly, sometimes it help to lube it and use a screw driver to flip latch/lock to locked position and then release with key or trunk release button several times. Rust is prone to jam locks and latches. Most local auto parts stores carry these latches in stock, and it is relatively easy to change out. Let me know if you need further help.