You cant drive the 74xx series at 12v. They are 5v only. You can drive 4xxx series at 12v, but I dont think you can do that with all of them.
Read the datasheets! There are tons of them on the net.
If you dont have a part number of the fet I cant help you with that, although odds are the pins are gate-drain-source. It sounds like it is still OK. Did you know they are sensitive to static electricity? So handle them carefully.