1998 ford f250 , starter won't engage

Do you have power at the starter when the key is in the start position?
Could be a dirty or loose connection between the battery and starter, or something else.

sounds like you have a issue going on with the ignition switch

Check connection battery,could be starter.

Check the igntion signal to the starter solenoid.

You need answer some questions first to rule some things out.
Is the starter making a noise when you turn the key or is it just clicking? If the lights light, but the starter makes absolutely no noise, then the power cable to the starter is bad or contacts are corroded. If you hear a click every time you turn the key but that is all, then the starter is bad and needs replace. Once it is removed, most parts stores can test it for you. If you can hear the starter spinning but its going real fast then again the starter is bad. If the starter is working properly (like on a really cold day when it doesn't start right away) but the car still won't start, then the starter is fine and your problem is either in the ignition or the fuel system. You may be able to narrow it down if you can read the codes, otherwise it needs a mechanic and you need to decide what is the car worth to you.

more then likely its a bad starter. or the cable to starter.

check for voltage going to the small terminal on the starter with the key on start, if yes bad starter if no go to ignition switch

You said you tightened the battery cables, did you check the other end of the negative where it bolts to the engine. When you tightened the cables you also used a battery brush and cleaned the posts and ends?

I have a 1999 f-250 super duty, v-8, it was good all day the day before, yesterday I was going to drive it to town, would not start, power is good, lights come on, turn key no response.