Dead links and Missing pages are redirecting itself to Main Page but with except

I hope my problem can be solved through this forum

I wanted my site to handle dead and non-existent links by displaying the 404 error page- Instead I noticed that it redirects these non-existent links and missing pages to the main page like for example – mysite.com/non-existent-link (redirects to) mysite.com/non-existent-link with no apparent changes to the url.

Another problem is, when accessing the following URL: mysite.com/genre/comedy – the intended page loads up fine but upon accessing mysite.com/genre it redirects to the homepage when it is supposed to display the error page

Only Exception when the error page actually works is when, links such as these mysite.com/+16476567> or mysite.com/444 or mysite.com/genre/gibberish are in use.

I have spent hours modifying the htaccess with different parameters, used default setting for permalinks and tried tweaking the template. But all in vain

Wish someone could throw some light on the problem

[No bumping, thank you.]