Help Please!!

Was messing about with my site and started editing widgets.php file, now the site loads up but it seems that anything to do with logging in or out and changing widgets has stopped working! I tried replacing widgets.php with an original file from a different installation but this hasnt worked!

Any help much appreciated, this is the error shown after attempted login.

Warning: Cannot modify header information – headers already sent by (output started at /home/www/designermatchup.freehostia.com/wp-includes/widgets.php:1571) in /home/www/designermatchup.freehostia.com/wp-login.php on line 267

Warning: Cannot modify header information – headers already sent by (output started at /home/www/designermatchup.freehostia.com/wp-includes/widgets.php:1571) in /home/www/designermatchup.freehostia.com/wp-login.php on line 279

Warning: Cannot modify header information – headers already sent by (output started at /home/www/designermatchup.freehostia.com/wp-includes/widgets.php:1571) in /home/www/designermatchup.freehostia.com/wp-includes/pluggable.php on line 595

Warning: Cannot modify header information – headers already sent by (output started at /home/www/designermatchup.freehostia.com/wp-includes/widgets.php:1571) in /home/www/designermatchup.freehostia.com/wp-includes/pluggable.php on line 596

Warning: Cannot modify header information – headers already sent by (output started at /home/www/designermatchup.freehostia.com/wp-includes/widgets.php:1571) in /home/www/designermatchup.freehostia.com/wp-includes/pluggable.php on line 597

Warning: Cannot modify header information – headers already sent by (output started at /home/www/designermatchup.freehostia.com/wp-includes/widgets.php:1571) in /home/www/designermatchup.freehostia.com/wp-includes/pluggable.php on line 770

/home/www/designermatchup.freehostia.com/wp-includes/widgets.php:1571

Also, presumably 1571 is relating to the line number in widges.php, yes?
If so the code only goes up to line 1569 and a blank line on 1570…