HELP !!!

I was in manual testing for 2 years. Left my job. Joined scaler. Cleared some mock interviews (except DSA). I am in desperate need of a job in developer role(full or backend). I need to clear DSA and ReactJS mock interview in order to be eligible for placements at scaler. I don’t see any other option now. And talking about DSA I don’t feel confident enough. Sometimes I go blank when there is a question. I don’t know to prepare DSA smartly and fast. Kindly suggest what should I do. (I’m not that bad at DSA. It’s just I’m not confident enough). So.. I’m open to all kind of possibilities and suggestions.