The Mt. Everest or Solu Khumbu region is the second most popular trekking area in Nepal. It would probably be the most popular destination. To get near Everest, you must either walk for a week or fly to Lukla, a remote mountain airstrip where flights are notoriously unreliable.
Solu Khumbu is justifiably famous, not only for its proximity to the world's highest mountain (8,850m), but also for its Sherpa villages and monasteries.
A trek in NEPAL is a special and rewarding mountain holiday. If you have the time and energy to trek,don't miss the opportunity to trek and see the COUNTRY'S spectacular beauty and unique culture. Fortunately for visitor, there are still only a few roads extending deeply into the hills.
Central Nepal is dominated by Annapurna Himal and the town of Pokhara. There are three major trekking routes in this region; to Jomsom, to Annapurna sanctuary and a circuit of the entire Annapurna massif. Pokhara is also a good starting place for number of shorter treks around Annapurna region.The ancient kingdom of Lo ( Mustang) is also geographically a part of the Annapurna region, but because treks to Mustang are subject to especial restriction.
Trekking for Langtang region can be started from Kathmandu. And this region is very convenient for both group and single traveler. Most of people are Buddhism.The region north of Kathmandu offers a multitude of trekking destination, all accessible without flights. The major areas are Langtang, Gsaikunda and Helambu, which can be combined in many different ways to make treks offer an experience not found elsewhere. The trails are challenging with long, steep climbs and descents, often though deep forests or across glacial moraines. 
The regulation for the restricted areas are supposed to protect the environment and culture of remote region and to provide security, both for the safety of trekkers and the protection of Nepal's northern border, To visit restricted area required to obtain an especial permit for the particular destination and also it is quite expensive. But the places are very unique and less travelled. it can probably be announced unexplored destination in the world. These areas are restricted in Nepal.
Trekking goals in eastern Nepal include an eastern approach to Everest, the remote base camp of Makalu, and the area near Kanchanjanga. There is endless variety in this part of the country. Most ethnic groups are represented and many villages, such as Dhankuta, Khandbari and Bhojpur are large, prosperous and clean.The area has hot rice-growing districts and also encompasses the cooler tea-growing region of Illam. 
Many people described Western Nepal is an unexplored destination. Western Nepal was once the centre of a large empire that extended in to Tibet and India and it now has a large population of both Hindus and Buddhists. It is remote and unknown from the western viewpoint because of its relative inaccessibility and its distance from Kathmandu.
