My duaghter came to live with us for 4-5 months bringing her 2 female and male cats which were not spayed or nutered. Now They are all gone but my house smells terrible, like cats in heat. How can I get rid of the smell?

my daughter came to live with us for 4-5 months and broguht her 2 cats, male and female, who were un nutered and not spayed. Now they are gone, an dmy house smells terrible, like a cat in heat. when people coem to visist they comment on the smell. PLEASE help me, how can i get rid of the smell???? Donna jean