How to achieve the following...

Good day,
quite a strange problem, but can't solve it on my own :) Let's say, I have Google Mail login page, saved locally to C: disk. I want to edit its source so, that when entered username and password and clicked on "Login" button it did absolutelly nothing, but the form did not reset. I tried deleting from the source "form action = https"//....", "method = post", "onsubmit = ...". So, when the form is submitted, nothing happens(as I want it to be), but the field values are reset(what I want to avoid). Any ideas, please? I also tried inserting to source code "form onsubmit = return false", but the username and password values are still reset. I hope my question is understandable :)

You could just change the submit button's type from "submit" to "button" and remove any event handlers it might have. It would also be worth removing any names or ids, or anything else that might identify it to javascript.