Story of demon Viradha in Ramayana

 Story of Viradha is found in Ramayana when Sri Rama goes to Dandaka

 forest in his exile period.

Viradha was a huge demon. He had got a boon from God Brahma that no

 weapon would kill him. The boon made him arrogant and fearless. He roam

 around the world attacking all living beings. 

Viradha makes a sudden appearance before Sri Rama, Laxman and Sita.

 Before the brothers can understand what was happening, Viradha had

 snatched Sita.

Soon a fight started between Sri Rama, Laxman and Viradha. 

In a fit of rage, Viradha carried Sri Rama, Laxman and Sita, deep into the

 forest.

When they reached the dense forest, brothers decided to kill Viradha.

The brothers cut off the arms of Viradha. The demon finally fell on the

 ground.

As the demon could not be killed by weapons, the brothers decided to

 strangle and bury him. 

That time, he started to tell his story. 

Viradha was the gandharva by the name  Tumburu . 

He was cursed by Kubera to born as a demon. 

Kubera had said that Tumburu would be relieved of his curse when Sri

 Rama defeats him in a fight. 

When Viradha got buried, he regained his original form as the  gandharva.