Windows LAMMPS....

I don’t think the format you save your file in matters too much, but typically LAMMPS input files have the .in file extension.

I seem to recall you stating in a previous email that it gives you the error that it doesn’t find the file. This is why you need to verify that your command prompt is in the correct directory and that you are using the correct name for you LAMMPS executable.

You should get one of the pre-made examples to work before trying to build your own input file from scratch. But it sounds like the issue is more with you not understanding how to use the appropriate Windows (or Linux) tools to run the program. This is not something the mailer list can really help you with, so my original advice of finding someone locally to help you still stands.