do a search on machine gun door locks.

If your trunk cannot lock then it's the trunk lock. If it locks then your trunks OK.

If it's always your driver door then it's the lock for your drivers door that needs to be replaced. This can be done at home but involves removing and replacing pop rivets. If you don't know what that is then you'll need a garage to do the work. It's not that hard but just requires taking the door apart and taking the entire lock mechanism out which is one single unit. You reuse the lock cylinder. This is a very common problem. The part number depends on your car build date.