How To Fix php.ini File in apache server for windows and linux servers

hi guys, your website has very good information on php. but i was wondering i you could give me some help. i am getting an error on my php.ini file and i don't know why. it was working before. i was getting some memory error and now i don't get anything at all, instead i get a blank page. i've searched everywhere trying to find an answer but no luck. thanks