Flights from India to Italy are available from nearly all the international airports of the country. Airlines such as Qatar, Etihad, Air India, Jet Airways and many other airlines provide flights to Rome. Air India operates direct flights only from New Delhi and Bombay. From Rome, you can take a train to Naples, or rent a car, both of which will take you approximately 90 minutes.
Alitalia has several daily flights from Rome, which in turn is very well connected with other destinations in the world. The duration of the flight is just around one hour.
You can rent a car and use the A1 highway, which directly connects Rome to Naples. The travel timeis less than 2 hours but there could be traffic jams on the way.
On an average weekday, there are 40+ trains - but they all have different transit times. You can reserve tickets up to 60 days before your travel date from italiarail.com
There re several bus oeprators in this sector, and they generally stop at Piazza Garibaldi or Piazza Municipio
There are a couple of cruise ship operators such as MedMar group that offer passengers a ferry service from Rome that take you to the main port in Naples (Stazione Marittima).