What date did Sherlock Holmes die?
To answer your question, the date generally accepted by scholars
as the date that Holmes supposedly plunged into the Reichenbach
Falls is: Monday, 4th May 1891.
His death of old age or some other cause later in his life is
Sherlock Holmes was not a real person but a character created by
writer Sir Arthur Conan Doyle. This fiction hero "died" in the
story "The Adventure of the Final Problem" published in 1893 in The
Strand Magazine and then in "The Memoirs of Sherlock Holmes"
People were so concerned that Conan Doyle had to bring the great
detective back. In 1901 Sherlock Holmes reappeared in "The Hound of
the Baskervilles". The story supposedly happened before Holmes'
"death" at the Reichenbach Falls in Switzerland.
Holmes returned officially from the dead in the 1903 story "The
Empty House", which is the first story in the book "The Return of
Doyle wrote the Sherlock Holmes stories until 1927 though the
chronology of Holmes' adventures ends with "His Last Bow", at the
beginning of World War I in 1914.
Sir Arthur Conan Doyle died in 1930.