The notice requirements for a landlord (landlord's agents, employees) to enter a rental unit vary from state to state.  Usually 24 hours written notice is required prior to entry unless it is an emergency in which case no notice is required.  Except for emergencies, entry is usually required to be during normal business hours.  You can sue the landlord for breach of the covenant of quiet enjoyment.  The covenant of quiet enjoyment is included in every lease and prohibits a tenant from being disturbed in his/ her use and enjoyment of the premises.  Violating the notice requirements for entry into your rental constitutes a breach of the covenant of quiet enjoyment.If the manager retaliates against you; for example, by eviction, you could sue for retaliatory eviction.  Retaliatory eviction is an eviction when the tenant did not commit any breach of the lease; the landlord is retaliating against the tenant.