Why why not run

sanic C:\Users\sy\Desktop\server.py

No module named C found.
  Example File: project/sanic_server.py -> app
  Example Module: project.sanic_server.app


from sanic import Sanic
from sanic.response import text

app = Sanic("MyHelloWorldApp")

async def hello_world(request):
    return text("Hello, world.")

The Sanic CLI does not take a path, but rather a module:

$ sanic --help                                     

positional arguments:
  module                         Path to your Sanic app. Example: path.to.server:app

Also, see the docs

For example, if you initialized Sanic as app in a file named server.py, you could run the server like so:

sanic server.app --host= --port=1337 --workers=4

If you want to run it using the file path, you should use:

python /path/to/file.py

In that case, you will need app.run() in the file.

thank you very much thank you very much thank you very much