Hiya! This is a common occurrence for me- I have a 98 Sentra XE. I usually
can't use the passenger door lock or the trunk lock with my key, so I
understand your trauma. What I've done is gone to Advance Auto and
purchased a can of aerosol spray silicon- the kind that comes with the
little straw for spraying guidance. I insert the straw into the keyhole
and spray. The silicon lubricates the locks and lets me use the key again.
I do this every few months in each lock and it helps a lot. This is
because the original grease or whatever it is in the locks has worn off
and the silicon re-lubes it. The spray is $2-$4 and if it doesn't work,
you didn't lose a lot of money. I know it sounds ghetto but it worked for
me :-)