question regarding Non Parametric Test

Hi all,

I want to test the relation between dependent varaiable and other independent variables,

my sample is Companies registered in the stock market,

I will divide it into two groups with Quantitative Data

but one sample will be 29 company while the other around 54 company

so I Actually I donot know when to use non parametric test or parametric test,

I tested the variables using Regression Parametric test,

Can I use non parametric Regression? if so , what its name?
Secondly, if the sample size below 30 , does it indicate something like using parametric test?