LG RZ44SZ80: Is it bulb or ballast problem??

I think a new lamp would be around $200 give or take. I'd replace the lamp first as that's more likely than a bad ballast. Even if it is a ballast you can always use the new bulb down the road. Or call in a service technician to diagnose it. That should be an easy thing to check.

If your owners manual says it is your lamp based on the lights being displayed then that is always your first step.