Computer Science is actually a massive number of roles and skillsets, and you need to work out which particular skill set you want to have before you go looking for certification.

First, you have to ask yourself what you want to do in Computer Science? Hardware or Software or Emerging technologies? While we answer this, we assume you are a fresher with no background in IT / Computer Science or an IT / Computer Science graduate (who could not get placed on Campus or off-campus drive)

Second, based on your answer you take certification related to that area.

Do note the following points which give actionable insights while choosing a Software Programming field:
1.) Decide & choose any Programming Language which you would like to learn. If you are confused like most unemployed youth then toss a coin & choose between Java & Python.
2.) Join a Live Online Training class.
3.) Simultaneously study and learn Basics of Computer Science. Conceptual clarity (Eg OOPS concept, Data structures, Algorithms, etc) is a must.
4.) Do at least two to three dummy projects. More the better.
5.) Once you complete dummy projects, start applying for jobs.