"I cannot find my chicken."
Translation:Jeg kan ikke finne kyllingen min.
Because 'kan' is a modal verb, and other verbs used with modals do not need 'å'. Just like in English you wouldn't say 'I can't to find my chicken'.
Be careful, though, because some verbs like 'vil' are modal in Norwegian but not the translation for them in English, so you must pay attention to the rule for each case.