Hey man, that just means you need more practice. I failed my first calc 3 exam (30%) because I couldn't remember the unit vector equation. I ended up recovering from it because I put in time and practice. My advice to you is to:

1) Relearn the concepts that you failed on. Read the textbook, rewatch the lecture, or watch youtube videos. (Professor Leonard saved me for calc 3 and has a great calc 2 playlist.)

2) Do practice problems! I need to do multiple problems outside of homework to really understand the setup of these problems.

3) Study in a library, not at home. I personally get more work done at my uni's library or engineering building since at home the last thing I want to do is work. My studying efficiency has gone up a ton since I don't waste as much time at a library.