Warning: Cannot modify header information – headers already sent by

Hi all,

I designed a website a while back and had someone help me build it, but i can’t get hold of them to help me fix an issue i’m having. I’m getting an error message on the log in page for this website:

http://www.thefandangoekid.co.uk/wp-admin

It’s coming up with the following error message:

Warning: Cannot modify header information – headers already sent by (output started at /home/content/38/11271038/html/thefandangoekid.co.uk/wp-content/plugins/woo-product-slider/main.php:214) in /home/content/38/11271038/html/thefandangoekid.co.uk/wp-includes/pluggable.php on line 1171

Can anyone tell me how i can get back to the standard WordPress log in page for this site?

Many thanks in advance,

Matt