Legal Advice

I'm seeking legal advice for a friend regarding her former partner. Both are listed on the house deeds, but he currently resides there. Over a year ago, she moved out and has since been renting. She has consistently asked him to sell the house to provide her share of the proceeds or to buy her out. Despite promises, he has not taken any action and has now changed the locks without her consent, limiting her access to the property where some of her belongings remain, and her youngest son lives with her ex. She requested keys, but he refused, claiming it is within his rights. Would you be able to help and advise on what legal options are available to her in this situation?