If you mean won't start, check the cam and or crank sensor. If it won't actually crank then something is broke inside or just seized.
Check your ingnition cylinder ...
It is because your shifter has not engaged in its place properly ( in park, P), therefore the ignition does not sense that it is in place and it wont let it turn and be pulled out.
1988 cougar will not crank over
We do not understand "crank" and "turn over" are the same thing.
Check the timing belt.
check for cats
wont crank or wont start http://www.kick-fix.com/nostart.html if it wont crank backup 1 page find no crank.
Check for fuel Check for spark
try lifting up on the shifter and turning the key it maybe a bad Neutral safety switch
missing groung wire.
Crank shaft sensor need replaced or cam shaft sensor
try the fuel pressure regulator