need advice asap

Depends what you are interested in! If there is a club about it, join it, if not then create your own! Also look at internships in your areas of interest.

Don't be afraid to reach out to professionals! Find what you are interested in (for me it's bio) and reach out to people who have jobs in the field. For me, I started a women in STEM club my junior year, enrolled in a week-long summer lab program, did an internship with Mass General Hospital, and joined clubs around me. Never be afraid to reach out to people for shadowing opportunities, as that's how I found out about most of these extracurriculars. Also, (if you are into STEM), I would suggest checking out the Biomedical Science Careers Program offered by Harvard Medical School! They do webinars and in-person info sessions dedicated to helping people find extraciriculars and jobs in the field. Good luck!

Find things you are passionate about and ways to explore those passions. Colleges love to see passion and it's important to stay balanced by doing activities that you enjoy. Part of being a healthy, alert student! Clubs are a great option because you can work your way up in leadership. But there are many other ways, too. You can start a passion project from home or simply delve deep into a hobby. You can volunteer for organizations that support things you care about or that directly involve your interests.

If you want further help, you can reply to my comment. Tell me about yourself--what do you enjoy doing? what do you care about? do you know what career interests you? This will help me help you find ECs that fit you.

Also, about the grades, what's holding you back? Are you struggling to stay focused and diligent or are parts/subjects in school particularly challenging? This will help me offer specific advice on how to improve.