Landlords cannot just enter your apartment or home without prior notice.
A landlord is required to give you from 24 to 48 hours notice before they enter your apartment or home.
The only exception is that a landlord may enter your home or apartment without notice legally if they have to enter the home or apartment for an emergency such as water leaks, fire etc.
Other than that if it's not an emergency then the landlord must give you prior notice to enter the home or apartment.