Those involved in the project are figuring out their next steps, and it's possible filming could resume, said the source, who was not authorized to speak publicly about the discussions and requested anonymity.
Jerry Bruckheimer was set to produce the film with a script by Justin Haythe. Hammer was expected to play the title character, and Depp was set to be the Lone Ranger's partner, Tonto.
The Lone Ranger show — about a masked Texas Ranger who battles injustice in the Old West — first aired on radio in the 1930s and became a hit TV series during the 1950s. The movie adaptation was scheduled to be released Dec. 21, 2012.
The film would bring together Depp and Bruckheimer, who have collaborated on the wildly successful "Pirates of the Caribbean" franchise. That franchise has raked in billions of dollars in worldwide box office sales for Disney.