Cannot open site admin using cloudy-purple theme

Hi
I installed Cloudy-purple theme but it will not allow me to go to site admin either from the cloudy purple page (no admin link) or from wp-admin browser link.
I get this error:
Warning: Cannot modify header information – headers already sent by (output started at C:\xampp\htdocs\wordpress\wp-content\themes\cloudy-purple\cloudy-purple\functions.php:19) in C:\xampp\htdocs\wordpress\wp-includes\pluggable.php on line 868

So I am about to delete & reinstall my WordPress on localhost.
If anyone knows any more about this that could help me for the future I am grateful for advice, thanks