Fatal Error when Installing Jetpack 2.5

In order to login, you’ll need to delete JetPack using FTP to access the files on the server – you can find it here:

wp-content
    plugins
       jetpack

Then to fix this problem, see:

https://codex.www.ads-software.com/Editing_wp-config.php#Increasing_memory_allocated_to_PHP

Thanks WPyogi! I managed to delete Jetpack, which means I can use my blog again, but I can’t figure out how to change the allocated memory. I’m not particularly strong with FTP and changing codes :/

You have to do that in the wp-config.php file – scroll to the top of the article I linked to for a more complete explanation. If you need help with it, I’d suggest asking your hosting company.