Hi @Amol_Singbal,
pandas is not used in the assignment. If you think your assignment file is changed unintentionally and you would like to get a fresh copy of the assignment, please follow this instruction which will ask you to rename your current notebook so that the system can get you a new copy. You may then move your work in the exercises from your current notebook to the new one.
You should see this in the new copy.
Cheers,
Raymond