If you’re seeing the prompt >>>, it means that you’re at Python’s interactive prompt.
What you’re typing there is for the system command line, which on Windows is in a Command Prompt window where the prompt would be something line C:\Users\Suneel>.
Also, the initial & that you’re typing is specific to Linux, so you shouldn’t be using it on Windows.
On Windows it’s recommended that you use the Python Launcher py:
py c:/Users/Suneel/Desktop/python_work/files.py
In the second piece of code, file paths that contain backslashes should use raw string literals:
Do those files I can see in the File Explorer have extensions? I can see that “data_c.txt” does.
If they do all have extensions but they’re being hidden (which would mean that “data_c.txt” actually has 2 extensions?), I suggest you tell File Explorer to show them. That’s generally recommended.