WASHINGTON - Bert Weedon, a British guitarist whose popular “Play in a Day’’ instructional manual introduced a generation of rock stars to the power of the guitar, died April 20 at his home in Beaconsfield, England. He was 91.

Friends confirmed his death to British news agencies but did not disclose the cause.

Long before he gained fame as the author of a top-selling guide to the guitar, Mr. Weedon was known as a versatile performer who could play virtually any style of music at a glance. He performed with such renowned jazz artists as Stephane Grappelli and George Shearing, accompanied singers Frank Sinatra, Rosemary Clooney, and Judy Garland, and was a regular on BBC broadcasts in the 1940s and 1950s.

Mr. Weedon was an early rock-and-roll guitar star in Britain in the late 1950s, with a series of instrumental hits that included “Guitar Boogie Shuffle,’’ “Apache,’’ and “Nashville Boogie.’’ But when his instructional book was first published in 1957, he became something of a spiritual godfather to a generation of would-be guitar heroes.

Its title - “Play in a Day’’ - offered the hope of instant musical gratification. The lessons began at the most basic level, with an illustration of how to hold a guitar. Weedon taught novices how to get through many rock-and-roll songs with three basic chords and included pointers on how to play a few basic tunes.

His guide, which was updated through the 1980s, sold millions of copies, leading Britain’s Independent newspaper to call Mr. Weedon “the man who taught the world to play the guitar.’’

Eric Clapton, Mark Knopfler, Keith Richards, the Who’s Pete Townshend, and three of the Beatles - George Harrison, John Lennon, and Paul McCartney - studied Mr. Weedon’s book.

“I like to think that I’ve helped in some way to make the guitar the most popular instrument in the world,’’ he said in 1997.