I want to run an activity query (i.e. objective is to check which data lines have changed) within a user defined date range. Please advise what is the most efficient way to achieve this.

Is it possible to run such a report without having a date column i.e. does Access have a hidden line modification date that can be used in a search?

Look forward to your feedback - thanks!

For the query, I would present your users with a form where they would enter the beginning and ending dates of interest and reference the form controls in the query

SELECT field1, field2...
FROM tablename
WHERE datefield between forms!yourformname!nameofbeginningdatecontrol and forms!yourformname!nameofendingdatecontrol

Access does not have a built-in way of tracking changes (audit trail) to records, so it is something you will have to create. Allen Browne provides one way of setting up an audit trail; check out this link http://allenbrowne.com/AppAudit.html

Many thanks for the advice : )