By air
The fastest and most convenient way to go to Nepal is by airplane. There are many airlines that offer frequent flights to Nepal's sole international airport, Tribhuvan International Airport in Kathmandu, from major cities across the world. Qatar Airways, Emirates, Etihad Airways, Turkish Airlines, Air India, and Thai Airways are just a few of the many well-known airlines that operate flights to Nepal.
Overland
You can also travel to Nepal by land if you are already in a neighboring nation especially India. You can either take a direct flight from Delhi to Kathmandu or you can travel by bus from India. Several bus companies run frequent routes connecting major cities in Nepal and neighboring country like India. However, it's a long way to go, and the roads aren't always in the best condition.
No matter what route you take, it's best to prepare ahead of time so that everything goes off without any difficulties.