All those little "gizmos" that you use to do something in WP are called Template_Tags. The one that you broke is in the General Tags section and is called bloginfo.
What it does: depending on what parameter you use (see their list on the page linked above) ==> it will show it.
So, if you want the URL of your blog, you use this:
<?php bloginfo('url'); ?> - DON'T change anything, this little thingy is smarter than you think :) it knows exactly what to do...
The above little code you can also use like
<?php bloginfo('url'); ?>/about - and will provide a link to my about Page.