I was asked to make a few changes to a client's WordPress template. I logged in just fine, but when I went to edit the stylesheet and template files through the admin panel, it said the files were not writeable and directed me to the permissions page in the Codex.
After reading that, I then changed the file permissions through FTP to be 755 for all directories and 644 for files. From that moment on, the entire blog became a blank white screen, including the admin login.
Did I do something that can't be undone? I have tried changing the permissions to other levels, but nothing works now, period.
This is seriously bad, because I have been at this for hours now and haven't even been able to begin on the actual work I'm supposed to have done by morning. I would be eternally grateful for anyone who might have suggestions!