Singer Sinead O’Connor has been found “safe”, police in the Chicago suburb of Wilmette said.
Police had earlier issued an appeal to trace the Irish singer after she failed to return from a bike ride.
O’Connor was believed to have left Wilmette at around 6am on Sunday on a bicycle, but did not return.
It is not yet clear where O’Connor was found.
O’Connor scored an international hit in 1990 with her rendition of Prince’s ballad Nothing Compares 2 U.
The gifted but troubled singer-songwriter is known as much for her fierce and expressive voice as her shaved head and blunt criticism of the Catholic Church and other institutions.
O’Connor was sued this month by comedian Arsenio Hall over a Facebook post that stated investigators looking into the supplier of drugs used by Prince should question Hall. She also accused him of drugging her.
In November, she posted a message on Facebook saying she had taken an overdose at a hotel somewhere in Ireland. Irish police later said she had been found safe. The next month, O’Connor posted on Facebook that she had been detained in a hospital for mental health evaluation.
Her rendition of Nothing Compares 2 U topped charts from Europe to Australia, and earned O’Connor multiple Grammy Award nominations.
In 1991, O’Connor was named artist of the year by Rolling Stone.
But her blunt-spoken manner often drew criticism, especially in the United States.
In 1990, some US radio stations refused to play her music after she banned the Star-Spangled Banner from her show in New Jersey.
An outspoken critic of the Roman Catholic Church over the way it handled sexual abuse by clergy, she drew intense criticism in 1992 when she ripped up a picture of Pope John Paul II on Saturday Night Live.
Over the years O’Connor has voiced support for other young female performers facing intense public scrutiny, including Britney Spears and Miley Cyrus.
O’Connor, who was diagnosed with bipolar disorder more than a decade ago, has spoken of her mental health problems. She told Oprah Winfrey in 2007 that before her diagnosis she had struggled with thoughts of suicide and overwhelming fear. She said at the time that medication had helped her find more balance, but “it’s a work in progress”.
In 2012, O’Connor cancelled a planned tour, saying her doctor had told her to rest after a “very serious breakdown”.
O’Connor, who has been married four times and has four children, signed a deal in 2014 to write a memoir.