Find (with "dotAll" box checked):
Replace with:
Code:
<head><title>Unknown</title></head>
Then highlight multiple files and use the right-click->"Link Stylesheets" to relink your stylesheet like theducks mentioned.
Or replace with:
Code:
<head><title>Unknown</title><link href="../Styles/stylesheet.css" rel="stylesheet" type="text/css" /></head>
if you so like.