Are there any laws or restrictions for an employer to change work schedules in Nebraska? Meaning if employers have to give certain amount of days notice before a posted schedule change? If so is there any ramifications an employer has if say employee is unable to meet these changes because of a prior engagement?

No, there are no laws regarding when employers must post schedules and now much notice they must provide with regard to schedule changes.

Not only is there no such law in Nebraska, there is no such law in any other state, either.

I think that I found such laws in South Carolina California, and Maybe Orgean yesterday.

Then by all means post links to them.