Admin site not working! Theme issue

Hello, I had the not-so-bright idea of going in to my theme and trying to add some code. Then after I tried the additional code and it didn’t work, I pasted the code from the Word doc back in (I realize now I should have used Text Edit). Now I can see my website with no problem (veggiechick.com) but I when I try to log in to the wp-admin site (www.veggiechick.com/wp-admin), I get the following error…

Warning: Cannot modify header information – headers already sent by (output started at /home/content/64/10964564/html/wp-content/themes/colorwaytheme/functions.php:5) in /home/content/64/10964564/html/wp-includes/pluggable.php on line 1173

Please help!! I can’t make any changes to my website. Is there a way to fix this code without reinstalling my theme?? Thank you!

Christin