I am getting error 500.. My .htaccess is corrupted.

Delete everything in your .htaccess and put this code in:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

There are 2 htaccess files in root. Which one to choose?

Remove just one and in the one that remains, wipe everything that is in it and add the code I gave above.

I have done what u said but when I click a link on my post.. it goes to error page.

https://howfreelance.com/blog/

You have to go to the backend then Settings -> Permalinks. Update your permalinks then it should work.

You are the boss! ??
Happy ending!