after 4 yrs of career gap after graduation in civil engineering how to become a quantity surveyor or how to crack interviews provided I have a fake experience mentioned in resume?

Hello,
We do not appreciate providing fake experience in your resume.
Be honest, and try to visit construction sites and see if there are any vacancies or internships available. 
Without having proposed site knowledge, one can become a good QS. 
Also, learn QS software like- Excel and others that are popular in your region. I recommend you study the measurement codes and different types of measurement techniques.