Lexie,
First of all, congrats on the acquisition! Second, it's always helpful to use an honest, experienced real estate agent or broker when making a purchase like this. Everyone has provided great insight so far, but ultimately your obligations as the landlord and the tenant's obligations are defined in the lease. This is the unwavering legal document that says who has do what, when they have to do it, and how they have to do it. You should never waver yourself from this document. If you or the tenant are not following the terms of the lease, that party is in breach of the lease and need to be put on notice with intention to follow through on the implications of the breach. Usually this means that the tenants have to provide access (within reasonable common notice), have to cooperate in access to make repairs (if they don't they would be liable for any additional damage caused by delay in repair), and subject to paying for a locksmith because you had to change the locks because they wouldn't give keys or provide access. Is it always that simple? maybe not, but you should be firm with the tenants in your expectations as the landlord or the lease means nothing, and you will continue to have a hard time. If you don't have copies of the lease, then that's where the experienced real estate professional comes in handy. These would have been provided in the due diligence period or as part of the deliverables package prior to writing the LOI. Firm up on these tenants and tell them to shape up or they can find another place to live. This is your property now and you have to keep things in order to maximize your long-term potential and value.
