I have a DPOA but my sister obtained a court ordered guardianship without telling the court. Any advice?

my sister obtained a court ordered guardianship without informing the court of previously executed durable POA, a healthcare POA, advanced directive and medical surrogate. I have these documents and I am not sure what to do. They were executed prior to incapacity. My father and myself were not aware of the guardianship proceedings and all the court documents I have seen that were presented by her to the court were full of lies. I again tried to execute these documents because my father is being held at a nursing home across the street from his home and he wanted to go home, but the nursing home threatened to call the police on me and my father has repeatedly expressed his wish to go home. what can I do. can I sue my sister. how do I tell the court she lied. how can I get my POA to be honored by the court. I need help. my father has a great deal of money but my sister and the professional guardians are going thru it rapidly. my father had transfer upon death accounts. they already liquidated my life insurance policy my father was holding for me. how do I stop this.