I was not diligent in observing the teachings of religion until I was subjected to severe demonic possession. I went to a Shaykh seeking treatment and I am now recovering gradually. I have returned to Allaah The Almighty in repentance. What do you advise me to do?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

May Allaah The Almighty grant you a full recovery and keep you firm on the right path. There is no doubt that the devil gets closer to man whenever he strays further from Allaah The Almighty and vice versa. That is to say, whenever man draws closer to Allaah The Almighty, he becomes less likely to be influenced by the devil because he is no longer in his power. Allaah The Almighty Says (what means): {Indeed, My servants - no authority will you have over them, except those who follow you of the deviators.}[Quran 15:42] 

Thus, being far from Allaah The Almighty might have been the cause of what happened to you. Now, since you have returned to Allaah The Almighty in repentance, you must abstain from committing sins. At the same time, you must keep the company of the righteous, perform acts of obedience as much as you can and remember and mention Allaah The Almighty often and this is a strong shield against the devil and his soldiers. You should also repeat the recitation of Sharee‘ah-approved Ruqyahs (incantations) until Allaah The Almighty grants you a full recovery.

And Allaah Knows best.