I solved this another way. First of all I installed cuda 10.1 toolkit from this link
Where i selected installer type(exe(local)) and installed 10.1 in custom mode means (without visual studio integration, NVIDIA PhysX because previously I installed CUDA 10.2 so required dependencies were installed automatically)
After installation, From the Following Path (C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v10.1\bin) , in my case, I copied 'cudart64_101.dll' file and pasted in (C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v10.2\bin).
Then importing Tensorflow worked smoothly.
N.B. Sorry for Bad English