95 f150 will not crank

I know this answer is vague but not a lot of info to go on; inspect the charging system and ignition system. Charging system; starter relay, starter motor, battery cables, look for weak or intermittent connections, lack or loss of grounds. Ignition system; check ignition module or switch, there should be guides online for checking those with key on, key off, and what voltages should be present.