Advice on test to use

Here's a general description of the data:
at baseline, n=50, discrete data (Y/N), # of Ys =3
process done
follow up but now n=42 due to several drop outs, same question (Y/N), # of Ys = 14
What is the best way to determine if the change in number of Y answers is significant?
Also, when conducting the analysis, just use n=42?
Many thanks in advance