Help with a fatal error! :(

Ok, so I’m having a lot of problems and I’m really hoping it will be fairly easy to fix. I literally stayed up all night getting the forums going, and then I had issues with having ti deactivate a captcha since it prevented people from logging in on my forums. I got a lot of spam comments as a result, and when I tried installing a different captcha program, it would not activate because of the size limitations.

I found this site https://perishablepress.com/press/2008/02/17/wordpress-error-fix-increase-php-memory-for-cachephp/ and installed what they asked me to, put it into my wp-includes section, and now I’m getting this fatal error:

Fatal error: Call to undefined function wp_cache_init() in /home/melonie/public_html/wp-includes/load.php on line 378

my website is meloniemac.com. Someone please help, I am so scared that I’m going to lose all of those hours of work I put into it last night. :/