Can’t login to blog

I began getting error messages on my blog, Wedding Decorator, the other night. I believe it began happening after upgrading the WP-Super Cache plugin.

When I try to login I get this message:

Warning: Cannot modify header information – headers already sent by (output started at /home/darleene/public_html/wp-includes/class.wp-styles.php:49) in /home/darleene/public_html/wp-login.php on line 255

Warning: Cannot modify header information – headers already sent by (output started at /home/darleene/public_html/wp-includes/class.wp-styles.php:49) in /home/darleene/public_html/wp-login.php on line 267

Then, when I enter my information, I get these error messages:

Warning: Cannot modify header information – headers already sent by (output started at /home/darleene/public_html/wp-includes/class.wp-styles.php:49) in /home/darleene/public_html/wp-login.php on line 255

Warning: Cannot modify header information – headers already sent by (output started at /home/darleene/public_html/wp-includes/class.wp-styles.php:49) in /home/darleene/public_html/wp-login.php on line 267

Warning: Cannot modify header information – headers already sent by (output started at /home/darleene/public_html/wp-includes/class.wp-styles.php:49) in /home/darleene/public_html/wp-includes/pluggable.php on line 649

Warning: Cannot modify header information – headers already sent by (output started at /home/darleene/public_html/wp-includes/class.wp-styles.php:49) in /home/darleene/public_html/wp-includes/pluggable.php on line 650

Warning: Cannot modify header information – headers already sent by (output started at /home/darleene/public_html/wp-includes/class.wp-styles.php:49) in /home/darleene/public_html/wp-includes/pluggable.php on line 651

Warning: Cannot modify header information – headers already sent by (output started at /home/darleene/public_html/wp-includes/class.wp-styles.php:49) in /home/darleene/public_html/wp-includes/pluggable.php on line 850

I was able to work in WordPress despite the messages the other night, but now I can’t login at all. Any help would be appreciated, thanks!