UVs are viewed and edited in the 2D view of the UV Texture Editor ( Edit UVs > UV Texture Editor). UVs display whenever a polygonal or subdivision surface mesh is selected in the scene view. When the 3D mesh is de-selected the UVs are no longer displayed in the UV Texture Editor.
By default, all of the UVs for a selected object get displayed. You can display a subset of UVs using the Isolate Select feature. For more information see Display a subset of UVs.
To display UVs in the UV Texture Editor
The UVs for the selected mesh are displayed in the UV Texture Editor.
The UVs associated with the vertices you selected on the mesh are displayed in the UV Texture Editor.