Dear Sir, My problem is that whenever I do any activity I check it for 3-4 times. for example, When I do Lock or powered Off Eletrical Switch or Close Water nobe or do any mathematical calculation etc. I check it 3-4 times. I know that I did it correctly however I check again and again. Please provide me the solution.

These are symptoms of Obsessive Compulsive Disorder, mental illness due to chemical (called serotonin) disturbances in brain. You need to consult Psychiatrist for the treatment. There are medicines, which can correct Serotonin imbalance. He will prescribe them.