You Do Need power plug adapter while traveling from Nepal to Guyana.

Here is Why You Need An Adapter

The outlet and plug type used in Guyana are A, B, D and G and in Nepal are C, D and M. This is how they look like.

Nepal

In Nepal, outlets of type C, D and M are in use.

Type C

Type D

Type M

Guyana

In Guyana, outlets of type A, B, D and G are in use.

Type A

Type B

Type D

Type G