I'll let you in on a dirty little secret: scientists don't jump into the battle unless they think they already have a solution to a specific problem, or at least a very strong suspicion that they have one. This is summarized by the old "Art of War" quote: "never start a battle that you have not already won." Believe me, these are wise words that will help you throughout your life.
This is not to say you should not take on great challenges, far from it. It means that you should take on challenges against which you have special knowledge, skill, ability, and understanding that will empower you to meet and defeat them. If you have a specific unsolved problem in mind and think you have a good solution, then maybe you should try it. Even if you fail, you can describe your approach and why you thought it would work. If you just want to haul off and attack some random unsolved problem without knowing much about it, well, I would probably recommend against it.
There are infinite things you can do with computer science or with computing in general. Computer programming, for instance, is a cross between literature and magical incantations. It is limited only by your imagination. Think of some unmet need that can be solved via a clever web application or computer program and try to create a solution for it. What are your hobbies? What computing equipment do you have? What programming skills do you have? Do you want to do a hardware project?
These questions will help you brainstorm an approach to your project.
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