wp_enqueue_scripts not firing

This is definitely a fringe case, but make sure you don’t have any new lines at the top of your header.php file. I’m not sure if this is standard, but the server that I was working on erased the contents of the file because there was a newline at the top of the header.php file. I think the normal error is something like “Headers already sent”. Since header.php is where wp_head() is called, wp_enqueue_scripts wouldn’t fire.