Why did the Sepoy Mutiny fail?

The Sepoy Mutiny failed due to the following reasons:

• Although the Hindus and Muslims had a common enemy , they were not exactly on friendly terms with each other.
• The rebellion lacked effective coordination with which they could not fulfill their objectives.
• The mutiny took place mainly in the northern part of India, with little to no support from its brethren from the south.

For further reading check the following articles:

• Revolt of 1857: Economic Factors
• Revolt of 1857: Immediate Factor
• Revolt of 1857: Observations by Historians