why did gandhiji start Non coorperation …

Gandhiji launched the Non-cooperation movement of 1921 because: 

• According to Gandhiji , the British rule was established in India with the cooperation of Indians, and had survived only because of this cooperation. So time has arrived to withdraw cooperation to the British. 
• First World War added to the misery of the Indian people. Heavy taxes, high prices, famines and epidemics made people's life miserable. 
• Rowlatt Act invited large scale protests throughout the country. 
• Jallianwala Bagh Massacre and the injustice done to Punjab made Indians angry which needed to be avenged.
• To restore the status of the ruler of Turkey. 
• To bring Swaraj or Self Rule to India. 
• Mahatma Gandhi declared that the main objectives of the non cooperation movement were : 
• To cripple the British administration and make them realize that they cannot function without the actual support of the Indians. 
• To avenge the wrong done by the Government in Punjab (Jallianwala Bagh Massacre) in a non violent way. 
• To bring about unity among the people. To inculcate a sense of nationalism. 
• To promote khadi and to attain Swaraj.