Rosemary and Rue by Seanan McGuire (2009) DAW Books

October Daye is a changeling, her Mother is a Daoine Sidhe and her father is human.  She was a licensed private investigator in San Francisco, then she was hit with a curse and spent 14 years as a fish in a pond.  Eventually the curse wore off and she returned.  But she was declared dead and her former partner and her daughter won’t see her, and she lost her license.  She thinks everyone is mad at her and refuses to see anyone else or answer her phone.  But when she does check her messages, a powerful Sidhe has left another curse on her and she must find the fae’s murderer and bring them to justice or die herself.