l just recently got a 94' mercury sable and the car key wont open the trunk and l dont know how else to get in the trunk, because the backseats dont come down to get through from the inside of the car. any suggestions?

there should be a pass through, possibly where the armrest is if u can open that, some cars have a trunk release that is reachable from this position pull the release & the trunk should pop open
if that fails, u may want to take it to the dealer & as a precautin have the lock replaced or have them at least find out how to open the trunk

you may also be using the wrong key, most car keys r 3 sets 2 masters (which can open all doors & trunk) & a valet key (which typically cannot open the trunk) check to see which key u have

but if all else fails take it to the dealer

There should be a trunk release button somewhere by the headlight switch and hood release. Ford/Lincoln/Mercury is only come with 2 keys and those work for everything. There are no valet keys.