Here is a chart that shows twelve countries and one economic bloc offering PTAs to Nepal. They are Australia, Canada, EU, Iceland, Japan, New Zealand, Norway, Switzerland, Turkey and the US (offering GSP facility); and China, Chinese Taipei and Republic of Korea (offering LDC-specific PTA facilities).
Don’t confuse PTAs with RTAs. Nepal is signatory to three RTAs (India-Nepal, SAFTA, SAPTA; BIMSTEC is yet to come into force). Here is a brief trade profile of Nepal.