The interviewer wants to know that you can think outside the box or even ask for help when you are stuck on a complicated problem.
Maybe you look to a mentor or boss for advice. Perhaps you turn to handbooks, manuals, and systems for help. Offer some relevant examples based on your industry. If you work in the medical field, you may turn to textbooks, online research, colleagues, or even a patient's history to find the right solution. If you work in customer service, you may ask the customer what they need to find the best way to solve the problem.
Show the interviewer that you are knowledgeable and equipped to handle these types of scenarios.