If it does not work, you may try by placing the php.ini file in your directory which executes upload process.
If your server administrator restricted the usage of php.ini then you may overwrite php settings using .htaccess file. Open notepad and paste the below code and save the file as ".htaccess" file and place it in the domain root directory.
php_flag safe_mode off
php_value max_execution_time 1000
php_value session.gc_maxlifetime 14000
php_value output_buffering on
php_value upload_max_filesize 104857600
php_value post_max_size 104857600
php_flag display_errors off
If both the above options does not work, then you may need to ask your server administrator for increasing file upload size.
The administrator has disabled public write access.