The key and steeeing wheel are not connected on a 1969 Thunderbird. I don’t think the wheel actually locks at all (I have never tried this on my 1969 Thunderbird). The ignition switch is underneath the dash. Also your post is really vague. It gives us like nothing to go on. Could you please be more specific?
If the key will not turn then your ignition switch is busted or something is binding it up. It could be the tumblers are worn out or you inserted the wrong key. Also by the wheel won’t lock down are you referring to the tilt-away feature? There is a locking pawl that locks the wheel after you pull it down into position. Sound like there is something wrong with that. So that means the wheel has to come off and you need to inspect the column mechanism.
Often the pins holding the locking pawl come loose or fall out making the pawl become misaligned. Is this happens you could have an issue where the tilt-away will not lock into place.