Question

why does Helen consider the old fashioned garden as a paradise of her childhood

Answer 1

Helen Keller enjoyed playing in the garden as a young child because she could enjoy it with the senses other than hearing and seeing.

From a very young age, Helen Keller loved nature.  She describes how she used to spend her days playing in the garden before her teacher Anne Sullivan came and taught her how to communicate with the world.  She did not need to have all of her senses to enjoy the garden.