No problem with the battery and alternator and spark plug

The windows won’t go up or down

Sat nav screen has gone dim is it a bulb

My sportage works great, except when it doesn't start. It can go days, weeks, months with no problems, then will simply not start. It turns on, does a system check, lights work, windows, etc.; however… 

Car ran out of petrol, put petrol in but car won't start. Any ideas???