If you don't think your query should be prompting for a parameter but it is,
odds are you've made a mistake in the query. or, if this is happening when
you open a form or report, you're referring to a field that doesn't actually
exist in the underlying table(s).
Make sure that all fields referenced in the query still exist, and that
you've typed their names correctly.
If this is for a form or report, make sure that the ControlSource property
for each bound controls on the form or report points to a valid field. In
reports, check that the Sorting and Grouping dialog doesn't point to
non-existant fields.