I have a Web Part deployed on a SharePoint site.

The Web Part have some search functionality and when the user clicks a button a CheckBoxList is genereted based on the results of the search. Now the user can select/deselect items from the list and then click another button the should have some other functionality.

My problem is that when the second button is clicked and the page returns the CheckBoxList is now empty. How should a Web Part be designed if I want this two-step thingie to work. I can't seem to figure it out.

Try to wrap your codes in !IsPostBack method

if(!Page.IsPostBack) 

{

 //Place your codes here for generating CheckBox list

} 

Thanks for your answer, but it didn't help much, it's like it completely drops any knowledge about the checkbox list when the second postback happens

Have you enabled viewstate and session? Just to check if its that

Are you adding the checkboxes in the OnInit? If you havent added the checkboxes in the init, they will not be apart of the viewstate, hence their state is not conserved.

Might consider using session to store some states :)