Allison,
Glad you’re back up.
You should “copy” your functions.php and your .css and any other code file and save it as a safeguard. Editing the functions.php via the Admin panel thru your WordPress theme (control panel) is risky. If you goof up any punctuation, or leave off a { ” or . or anything it can give the “white screen of death”.
Better to use your Hosting C-panel to edit, so you can get back in if a mistake is made, and use FTP.
Far, far safer.
(I’ve done it once. That cold, shiver you get the first time you do it is not fun).