What are the rights of a renter in Maryland, when the owner wants to sell? And what if the lease was month - month? Does the renter have any rights in this situation?

I don't know if Maryland is different than most states but around here the buyer is your new landlord and no changes can be made in your lease. However reread your lease carefully to insure a clause regarding selling the property was not included. In most states you are good until the end of the lease. If the new buyer is doing this as an investment he may be happy to keep you on and maybe even extend.

If you are on a long term lease then the buyer has to honor the lease. If you are on a month to month lease, either the current owner or the buyer can terminate your tenancy with notice equal to one rental period.

You have the right to require reasonable notice to show the property, but you can't refuse access totally.

What you need to find out from your current landlord is if he is selling the property as rental property or as owner occupied. If he says whatever the buyer wants, then I suggest you start looking for a new place to live.

If your lease is month to month ( then it is really a rental not a lease) but all the current owner or the buyer has to do is give you one month notice to have you move out, or to raise your rent.

If you were in a long term lease ( 1 or 2 year) the new buyer has to honor all of the terms of the lease when they buy.

You will have to allow access with notice for them to show the property.