InfoPath Dev

Is there a way to reconfirm changes made to the checkbox.

What I mean is, I am trying to make something readonly the moment someone clicks a checkbox. However, I want the user to see a warning sign saying "Are you sure?" with options to select "Yes" or "No". Upon selecting "No" the changes made to the checkbox will go back to initial state. Is this possible?

You'll need a secondary field and a section to help you out.  When the checkbox is checked, display a section that asks you yes or no.  If the user answers yes, then you can dismiss/hide the section again and leave the checkbox set to yes.  If they say no, dismiss/hide the section and reset the value of the checkbox to no.  Any additional logic that you want to key off of this checkbox will probably have to check when the checkbox is set to Yes and the secondary variable is set to Yes to ensure that they confirmed with the checkbox.  Hope that makes sense :)