Answer by taking a quote from the following article:

Black Sabbath were an English rock band, formed in Birmingham in 1968, by guitarist and main songwriter Tony Iommi, bassist and main lyricist Geezer Butler, singer Ozzy Osbourne, and drummer Bill Ward. Black Sabbath are often cited as pioneers of heavy metal music. The band helped define the genre with releases such as Black Sabbath (1970), Paranoid (1970) and Master of Reality (1971). The band had multiple line-up changes, with Iommi being the only constant member throughout its history.

The remaining two original members, Tony Iommi and Geezer Butler, began auditioning new singers for the band's next release. Samson's Nicky Moore, and Lone Star's John Sloman were considered and Iommi states in his autobiography that Michael Bolton auditioned for the band. The band settled on former Deep Purple vocalist Ian Gillan to replace Ronnie James Dio in December 1982. While the project was not initially set to be called Black Sabbath, pressures from the record label forced the group to retain the name. The band entered The Manor Studios in Shipton-on-Cherwell, Oxfordshire, in June 1983 with a returned and newly sober Bill Ward on drums. Born Again (7 August 1983) was panned upon release by critics. Despite the negative reception of the album, it reached number four on the UK charts, and number 39 in the U.S. Even a decade after its release AllMusic's Eduardo Rivadavia called the album "dreadful", noting that "Gillan's bluesy style and humorous lyrics were completely incompatible with the lords of doom and gloom".  Although he performed on the album, drummer Ward was unable to tour because of the pressures of the road, and quit the band after the commencement of the Born Again album. "I fell apart with the idea of touring", Ward later said. "I got so much fear behind touring, I didn't talk about the fear, I drank behind the fear instead and that was a big mistake." Ward was replaced by former Electric Light Orchestra drummer Bev Bevan for the Born Again '83 -'84 world tour, (often unofficially referred to as the 'Feigh Death Sabbath '83 - '84' World Tour) which began in Europe with Diamond Head, and later in the U.S. with Quiet Riot and Night Ranger. The band headlined the 1983 Reading Festival in England, adding the Deep Purple song "Smoke on the Water" to their set list.  The tour in support of Born Again included a giant set of the Stonehenge monument. In a move that would be later parodied in the mockumentary This Is Spinal Tap, the band made a mistake in ordering the set piece. As Geezer Butler later explained:  We had Sharon Osbourne's dad, Don Arden, managing us. He came up with the idea of having the stage set be Stonehenge. He wrote the dimensions down and gave it to our tour manager. He wrote it down in metres but he meant to write it down in feet. The people who made it saw fifteen metres instead of fifteen feet. It was 45 feet high and it wouldn't fit on any stage anywhere so we just had to leave it in the storage area. It cost a fortune to make but there was not a building on earth that you could fit it into.

How did Born Again do on the music charts?
Despite the negative reception of the album, it reached number four on the UK charts, and number 39 in the U.S.