"Could not happen" vs. "could have not happened"

Which one is correct?

These changes could have not happened without outstanding help kindly provided by the queen.

These changes could not happen without outstanding help kindly provided by the queen.

The changes happened last year and thus the process of changing is done.

These changes could not have happened . . . describes changes that have already been made. These changes could not happen . . . describes changes which are currently being made.

I would use neither but write

These changes could not have happened without outstanding help kindly provided by the queen.