I have headlights but no power inside or to start

Sometimes, a headlight may start flickering due to physical damage to headlight components. The inside of the connector may start to melt, causing a poor connection. the bulbs or lamps of your headlights are old or damaged, it can cause the headlights to flicker. Fortunately, this can be a relatively quick fix.

When the alternator starts to give out, your car’s electrical output is affected. This could result in flickering, dimming, or inoperative headlights, as the headlights depend on power from the vehicle's battery. When the alternator is unable to charge the battery, the vehicle's electrical system will quickly drain the battery. One of the most common causes of headlight flickering is a dying battery. Your headlights rely on power from the battery to function properly. If the battery is failing, flickering, or dimming headlights may be the result. In this situation.

Dim headlights are almost always caused by a corroded ground connection. But sometimes it can be caused by corrosion inside the headlight connector.

I guess you are saying that after you turned the ignition off, the headlights and all lights went off, but when you returned and turned ignition on all lights but the headlights came on. "a gremlin" stole my light switch? Possible, but most likely your headlight switch is bad, or the headlight relay, or if the dimmer switch makes no difference, It could be power supply or connection to the headlight dimmer relay is bad. Corrosion causes funny behavior. Clean bright metal connections make a world of difference. Follow headlight wiring back to a small box usually on the inside fender of the Engine bay. Check all connections including the ground to the frame (body metal).

The headlights get power thru a built-in circuit breaker inside the headlight switch, and the switch gets power from a fuseable link wire.
The heavy red wire acts as a fuse if overloaded.

Are the headlights working ? If so they would pull current thru the switch and leave nothing for the meter.
If not you could have a weak connection between the headlight switch and the source of power, including inside the switch. The connection could be good enough to power the meter but not good enough to power the lights.

see this steps and fix it use the VOM or DVOM. God bless you
The Cause: Most likely no voltage to the headlights because of a bad headlight relay, fuse, module, headlight switch, dimmer switch or wiring fault.
To figure out what's causing your problem, start by inspecting the main fuse for the headlight circuit. See your Owners Manual for the location of this fuse. It is often located in the power center in the engine compartment, but may also be in the fuse panel under the dash.
If the fuse has blown, replace it with a new fuse (same amp rating) and try again. If the fuse blows immediately, there is a short in the headlight circuit that will have to be found and repaired before the headlights will work. If the fuse does not blow and the headlights work, problem solved (for now). There may be in intermittent short or overload that caused the fuse to fail.
If the fuse if okay, use a volt meter or 12-volt test light to check for power at the fuse. Most headlight circuits are on (powered) all the time, so there should be voltage to the power side of the fuse. No power at the fuse would indicate a wiring fault possibly in the fuse block or in the wiring between the fuse block and the battery. You'll need a wiring diagram to trace the wiring circuit and find the fault.
If the fuse is okay and there is power, the next check would be to find the headlight relay or control module. If the system uses a relay, pull it out and shake it. If anything inside rattles, replace the relay. Or buy another relay and plug that in to see if that restores power to the headlights.
On systems that use a module control module or daytime running lamps, about all you can do is eliminate other possibilities such as wiring faults, a bad relay or headlight switch first. If the module is getting power when the headlight switch is turned on, but the headlights fail to come on, the problem is likely a bad module. The module may be located in the front area of the engine compartment (common on Fords), under the dash or elsewhere in the front of the vehicle. You will probably need to refer to the vehicle service literature to find the module's location.
If the headlight relay or module do not receive voltage when the headlight switch is turned on, a bad switch is your problem. Switches get a lot of wear and tear, so it's not unusual for a switch to wear out after many years of service. Replacing a headlight switch can be difficult depending on whether is it located in the instrument panel or on the steering column.
If your headlights work on low beam, but you have no high beam, or they work on high beam but there is no low beam, the most likely cause is a bad dimmer switch. The dimmer switch is integrated into the steering column mounted headlight switch on most vehicles, so if the dimmer is not working, you will have to replace the entire switch.
DO NOT attempt to replace a steering column mounted headlight switch without first disconnecting the battery and waiting at least 20 minutes for the capacitors in the airbag circuit to discharge. The steering wheel will have to come off to replace the switch. Crossing up the wrong wires in the steering column could set off the air bag and cause personal injury.
If a headlight switch looks like it will be difficult to replace, don't try to do it yourself. Take your car to a dealer or repair shop and have them replace the switch for you.

The headlight switch loads the dimmer switch either the headlight switch is bad or there is a connection problem either on the headlight plug or the dimmer switch plug.
Sometimes if the plug is partially melted or bulged it tells you that the connection has been arcing inside plug.

replace the headlight switch a circuit braker is bad insid the switch

If your car has the xenon headlights, it might be a faulty xenon ballast/regulator module. You car has daytime running lights so they are on at a low power setting all the time.

It sounds to me like you might have a loose headlight connector, or something is causing the conduit inside the headlight to shatter, if you take the car to work every day do you go over a big bump at all? also what brand are you using and what does Hyundai recommend using, the wrong headlight bulb can also make this happen - just because it fits doesn't mean its right.