Check boxes for showing categories

Although it looks like by default it has the categories as a dropdown select, it looks like this plugin could be slightly modified to fit your needs:

Taxonomy Picker

Taxonomy Picker is a widget which you can include in your sidebar to
help visitors build complex queries using categories and your custom
taxonomies by chosing terms from drop down boxes.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)