Sri Nathamuni went on a long pilgrimage that took him to Divya Desams like Mathura, Vrindhavan, Bengal and Puri. On his return to his home town, he met with some SriVaishnavas from the Western part of the country, who recited some 10 hymns composed by Nammazhvar. Realizing that they were part of much larger work, he decided to go to Kumbhakonam and then to the town of kuraka. This is where, the Guruparampara Prabhavam states, Nathamuni came in contact with Madhura-kavi azhwar, the disciple of Nammazhwar, and asked him if the hymns of Nammazhwar are available. Madhura kavi azhwar told him that, after composing an extensive book of hymns in Tamil and instructing him the same, Nammazhwar attained salvation. However, the local people, due to their misconception that the study of the hymns would be detrimental to the Vedic religion, threw the work into the river Tamraparani. Only one page, containing to hymns of the work, was picked up by a man who appreciated the hymns and recited them.
Thus only 10 hymns have been saved at this time. Nathamuni recited 12000 times a verse composed by Madhura kavi azhwar in adoration of Nammazhwar, who then revealed the purport of the entire work to him. Not satisfied, Nathamuni wanted to know all the words in detailed. He was asked to approach an artisan, who provided Nathamuni with the complete text of the work, which latter came to be known as TiruvAymozhi.
Nathamuni then gave the text to his disciple Pundarikaksa, who then gave it to his disciple Rama Misra, Rama Misra gave it to Yamuna, Yamuna gave it to Gosthipurna, who gave it to his wife Devaki Sri. Gosthipurna also instructed Sri Ramanuja on the work. Nathamuni brought the hymns together and with the help of his two nephews, Melaiyagattazhwar and Kilaiyagattazhwar, set them to music in the Vedic manner. From that time onwards, these hymns were sung in the temples and were regarded as Tamil Veda.
Nathamuni wrote three works:
He was also a great exponent in Yoga and practiced the Yoga of eight accessories ( ashtAnga yoga). PrapannAmrta says that he attained Vaikuntam by entering into Yoga in the city of AgangA.
Most of the biography presented he is from A History of Indian Philosophy
Vol 3 by S. Dasgupta.