Ozzy Osbourne is struggling to write his autobiography, because he can't remember anything that's happened to him.

The former Black Sabbath frontman - who successfully fought his addiction to drink and drugs - signed a reported $2 million book deal with publishers Little Brown almost two years ago.

Since then Ozzy's wife, Sharon, has completed two memoirs of her own but the rocker's release date keeps getting pushed back, and the tome is now set to hit the shops next May.

A source said: "I cannot imagine the book being ready in five months, because so far Ozzy hasn't written anything - he hasn't even got a ghostwriter yet.

"So it is going to be some time before the book actually appears, if it ever does."

Ozzy - who once bit a bat's head off during a live show - recently confessed his memory had suffered because of his drink and drug abuse.

He revealed: "My memory isn't what it used to because of the drugs and alcohol I've been living on for the best part of my adult life.

"I often get asked, 'Is it true you snorted a line of ants?' Knowing me, there's a very good possibility. But do I remember it? No way."