The 70-year-old actor, who was in Florence to attend the River To River 2012 Indian Film Festival, wrote about the "tragedy" on his blog.
"Major tragedy! My valet forgot to pack my laptop in Florence, and I have landed in the Isles without it... Livid and most upset...
"Luckily my CEO was still in Italy and has found it and shall be able to get it back but only when I reach Mumbai and home... My hotel in the Isles has very kindly given me a working mac and I am writing this on it... Its like the loss of the world... So... Darned...," he posted.
The seven-day long film extravaganza held a retrospective of Bachchan's films.
"It has been difficult to tear myself away from Florence and all the lovely people that looked after me, and those that showed their affection during the Festival.
"It makes the farewells seem so personal, tinged with just the right amount of emotion. It has been noticed often that the moment you start to get comfortable at a foreign destination, comes the time to leave...," he added.