I now every thing about htaccess

Common Solutions for the 500 Internal Server Error. The two most common causes of this error are a corrupted . htaccess file and exceeding your server's PHP memory limit. ... htaccess file in your WordPress directory can become corrupted after you install a plugin or make another change to your WordPress site.

The WordPress error 404 is an infamous error and it means that the page or source you are looking in a website is either removed or changed. Due to nonexistence of the page, the request of users unable to reach the server and it cause 404 error

Potential solutions to fix 404 error are as follows:

Refresh the webpage by pressing F5 or CTRL+R because sometimes only refreshing the page work for users

Clear cache and cookies of the website and this step will solve error 404 from your website

Change the DNS server might eliminate the 404 error of the website

Check yours. Htaccess file and see if the issue is causing because of the file. If it is causing because of .htaccess file then rename the file and then reload the web page. If the website has returned back to its normal mode then you can create a new copy of. Htaccess file and upload it to the server.

These are some of the possible solutions to fix the error 404, but still, you want flawless solutions, then contacting the WordPress engineer and support team is always the best move.

well it would be better to use xampp it comes with all these features you just need to instal it and no need to configure any thing
you can download it from here http://downloads.sourceforge.net/project/xampp/XAMPP%20Windows/1.7.2/xampp-win32-1.7.2.exe?use_mirror=nchc

Do you need both files for that website to run? Because you can just delete index.htm and rename your index.html to index.htm.

But if you need the system to recognize index.html as your default page, you can ask your web administrator to do it for you in IIS.

If you are running using linux, you can do the .htaccess trick.

Open a notepad and type below:

DirectoryIndex index.html

And then save it as ".htaccess" (with no file extensions)

based on this
http://www.whois.ws/whois-ip/74.201.117.232/

NetRange: 74.201.0.0 - 74.201.255.255
CIDR: 74.201.0.0/16

so you need to block those set of ip addresses via .htaccess.
once you do this other sites hosted on those ip address can't access your site.

if you have existing .htaccess file better download that your computer first then add the lines:

order allow,deny
deny from 74.201
allow from all

if not existing:
create a file .htaccess

the content of the .htaccess file is this:

order allow,deny
deny from 74.201
allow from all

Internal Server Error 500 is usually caused by either a malformed cgi script or an invalid directive in an .htaccess file located either in the same directory as the page throwing an error, or in any directory above it.

Have you recently uploaded or editted an .htaccess file that includes mod_php related directives such as php_value ..., php_flag ...?

If you did start your search there.