Why do I no longer see the light I used to see when I walk, on my arm, and when I read the Qur'an?

The light appearing on the arm cannot be definitively interpreted, but light generally signifies goodness, as in the Prophet's supplication. The questioner is advised to strive in acts of worship and to ask Allah for steadfastness and a good end. Obedience to Allah and adherence to the Sunnah of His Prophet are more important than any sensory signs.