Not finding PHP.ini file

Please help me to increase upload size as I am not finding PHP.ini file in root directory. I have also select the Show hidden files option as I have seen in a WordPress upload limit tutorial that selecting Show hidden files will visible the PHP.ini file but it’s not showing . What should I do now? I think If I put this in PHP.ini file it will resolve my issue as its mentioned in guide already but I am not finding the file. Please help me to resolve my issue.

upload_max_filesize = 20M
post_max_size = 25M
memory_limit = 30M