Engine will not crank, dashboard and windows not working

There's nothing to program and you don't have to replace the Engine Computer. Which model do you have? The Wrangler and Cherokee use a newer type of ignition switch that hasn't really been the cause of much trouble. The Grand Cherokee uses an older style that does develop some common problems, but there's three versions of that switch, and the one used in that model is less likely to cause trouble.

Specifically, what I'm referring to is the cam on the end of the key cylinder. The cylinder has to be matched to the ignition switch, but as a complete switch and cylinder assembly, they can be interchanged between the other models. The symptom for the cam on the end of the cylinder being broken is everything else appears to work normally, but the switch won't quite turn far enough to engage the starter. The dealer's parts department has a repair kit for that.

Regardless of which type of switch you have, unplug the connector, then check the terminals in that connector and on the switch for evidence of overheating. They'll be black or discolored, and the plastic around them will be melted. Let me know if you find that.

If everything is dead, including interior lights and the instrument cluster, the best suspect is a loose or dirty battery cable. Start by checking both cable clamps on the battery posts. If those are okay, follow the smaller positive wire to the under-hood fuse box and check that connection. That's the cause of everything being dead, sometimes intermittently, on all car brands. That's the red arrow in this diagram. Also follow the smaller negative wire to the body and be sure that connection is tight and not rusted. Let me know what you find.