You are using your website suddenly see your web page out and an error come with name "500 Internal Server Error" at that time your frustration increase to your hosting provider and service depend as per their policy and terms. May you get solution after couple of days so I'm sharing some solution towards this problem.

Reason Behind 500 Internal Server Error:

If you are using shared hosting plan than following problem may affecting-
Increase number of process: We are using shared hosting of WordPress it's allowed 25 process at a time and mostly all hosting provider follow same foot prints.
CPU uses exceed: When your CPU uses crossed more than 25% it's auto block your web page and give same error.
.htaccess corrupted: When your .htaccess file corrupted than your server unable to respond you clearly.

What is the solution of 500 Internal Server Error in WordPress ?

1- Goto your hosting control panel and open MySql Database, than repair your database.

2- Goto your public_html directory via ftp or cpanel and rename .htaccess file to .htaccess_old, reload your blog and check everything working properly or not ?
If blog opening but links not working than create new .htaccess file and copy all content of .htaccess_old and save on new .htaccess file.
3- Open wp-includes directory and add below line in your functions.php file.

define('WP_MEMORY_LIMIT', '64M');

(It's resolve the issue of low php memory).

4- Install WordPress Super Cache Manager to optimize your cache download from here !

5- If all above method failed to solve your problem than you need to un-install your plugins from WordPress dashboard.

Hope everything is fixed if not than ask your hosting provider to serve you better 🙂