I just bought a 1996 mazda 626 cronos, fell in love with it too quickly to notice all the problems and now im stuck with it... My key will open all the locks EXCEPT the trunk. I can press the trunk release from inside but cant open it from the outside. any advice on how to fix this or whats wrong with it?

 

The first thing to try is to use some lube like WD40 or liquid wrench. Use the supplied straw on the can to lube the internal tumblers. I have had this problem in the past with many type of locks, they just freeze up inside.

If that dosen't work, you will need to remove the lock cylinder and take it to a locksmith for repair or cut a key in the case it has been changed out. thats one downside to used cars. you dont know where they have been.