You must allow the landlord access to the apartment to inspect the premises, make repairs, or to show it to prospective tenants or buyers. Unless it is an emergency, like broken pipes flooding the apartment, the landlord must give you 24 hours' written notice and enter only at reasonable times.
If you refuse to allow the landlord reasonable access to the apartment, the landlord may go to court and obtain an order compelling you to allow access or the landlord may terminate the rental agreement. In either case, the landlord may be awarded attorney´s fees in addition to actual damages suffered due to your refusal to allow access. (§ 76-1423, § 76-1438)
If the landlord makes an unlawful entry or uses his right of access to harass you, you may get a court order to stop the landlord from abusing his right of access or you may terminate the rental agreement. If you have suffered damages as a result of the landlord´s abuse of the right of access, a court may award you actual damages and reasonable attorney´s fees.