Affiliate Marketing Secrets

dad died 2 years agol i was left his home. Worth 90,000. My sister was left it as well. My sister is a greedy person, and went behind my back, and rented it out, for 600.00 a month, to her daughter. I did not know this until tonight, when I went there to try and sell this house. ITS been on the market 2 years. I have no income. I want to sell this house, free and clear. Obvisously, my sister does not, as shes been making 600 dollars a month off of it, without telling me about it.
I want to sell it, Id sell it for very cheap- which is awful, because its a very nice home. I just need money,due to the economy.
what can I do? What are my rights? Does she have to sell? Should I go to the court house.
p.s I live in Maryland. If that matters. Allegany co., Maryland.
How can she hide the fact that shes been renting it out? ( to her daughter). there is no written lease. Just a verbal one. A secret one at that.
Any help is so appreciated, believe me.
This all just went down tonight. Someone is calling tomorrow morning, to give me an offer on the home. what can I do?? Help!!!!!
Thanks a Million
Mrs.Winner