I moved your question to a new thread, as it’s more likely to get support than an old thread.
Let’s Encrypt needs to check that you control your domain. It does this by placing a “token” in the .well-know/acme-challenge folder within your site, and then checking you can reach it externally. In your case this failed.
What command are you running ? (that will help us provide a better answer for you ).
In short, try placing a plain text file at /.well-know/acme-challenge/test in the “webroot” of your website (i.e. where your main index.htm or index.php usually is), with just the word “OK” in it. Then see if you can go to http://www.apexitsolutions.co.in/.well-known/acme-challenge/test and get that file.