PHP Change the Maximum Upload File Size

You need to set the value of upload_max_filesize and post_max_size in your /etc/php5/apache2/php.ini :

; Maximum allowed size for uploaded files.
upload_max_filesize = 40M
; Must be greater than or equal to upload_max_filesize
post_max_size = 40M

**replacing the 40M with the size you want, for instance, 100M.

OR ELSE

In .htaccess you should put configurations in IfModule tag, other than the Internal server error will rise

This is an example

<IfModule mod_php5.c>
 php_value upload_max_filesize 40M
 php_value post_max_size 40M
</IfModule>