What is the correct CSS selector for ASP.net checkboxes?
I tried input[type="checkbox"] + label , input[type="checkbox"] and input itself but none can select the checkbox.
ASP.NET CheckBox control produces HTML with input tag with type checkbox, so there should be no problem with standard CSS selectors.
I have copied a HTML produced by W3Schools example of using CheckBox control and tried input[type="checkbox"] + label selector and it worked - check this fiddle.
With this being said, I think your problem is somewhere else and you should carefully check yout code.
You don't need the quotes in the type argument.
To get the checkbox itself,
input[type=checkbox]
To get the label text,
input[type=checkbox] + label