If the Vice- President is not available to discharge the duties of the President and if the latter dies or resigns, the responsibilities of the office fall on
The Chief Justice of India
According to the President (Discharge Of Functions) Act, 1969 Discharge of Presidents functions contingencies.
1. In the event of the occurrence of vacancies in the offices of the President and the Vice-President, by reason in each case of death, registration or removal, or otherwise, the Chief Justice of India or, in his absence, the senior most judge of the Supreme Court of India available shall discharge the functions of the President until a new President elected in accordance with the provisions of the constitution to fill the vacancy in the office of the President enters upon his office or a new Vice-President so elected begins to act as President under article 65 of the constitution, whichever is earlier.
2.When the Vice-President, while discharging the functions of the President, dies, resigns or is removed or otherwise ceases to hold office, the Chief Justice of India or, in his absence, the senior most Judge referred to in sub-section (1) shall discharge the said functions until the President resumes his duties or a new Vice-President is elected as aforesaid, whichever is earlier.