my 2004 kia Sedona intermittently refuses to start. I have light, radio, electric windows but just doesn't turn over at all. If I leave it a few hours and go back to it, it'll start first time as if nothing was wrong. I've tried getting out locking and unlocking, or using my spare key thinking its an immobilizer problem but nothings seems to instantly work. Apart from this the vehicle runs fine and can be fine for weeks before happening again Any ideas?
It may seem unlikely but I've had similar issues on other vehicles caused by corrosion on the battery terminal posts or loose connections. The accessories can still work because they require less amperage and the ignition or starter can't get high enough amperage over a barely connected battery.
It could also be a loose connection to the ignition coil (probably not the ignition coil if your engine won't turn over at all) or starter depending on your specific symptoms. It's a good cheap place to start. If not then you can have an auto parts store check your battery and alternator for free. Alternators do really unpredictable things when they start to go from my experience.