My cousin moved into my home when I was out of the country without my permission and no rent agreement. Can she deny me entrance when I return?

  The question is whether your cousin has right of possession or is merely a trespasser. Your question raises many other questions. You had no idea she was there for 2 years? Who was taking care of the place? Did she pay any $ to you or pay other charges associated with the property?   Certainly you could evict her if there is no lease or other agreement (oral or written) in place . I need more info.