you can use correlation regression and independnet sample t test.

what is aim of your paper

What type of regression will be suitable for nonparametric data?

and please guide why not Mann Whitney U test for comparison of 2 groups nonparametric

My understanding is that with nonparametric data I need to use spearman’s for correlation, don’t know which type of regression, and Mann-Whitney U test for comparison of means.

Please correct me if I’m wrong

Samples independent or dependent

for comparison question they are 2 subgroups of an independent variable. But for correlation and regression questions that is between IV and dv

spearman correlation we can use when we have non normal distribution data