HTTP error 500 – big trouble

ARG!! I tried to add the search bar to my header widget. .
I meant to add the following to header.php, but accidentally added to functions.php. Now the site shows HTTP error 500.

<form method=”get” id=”searchform” action=”<?php bloginfo(‘home’); ?>/”>
<div><input type=”text” size=”18″ value=”<?php echo wp_specialchars($s, 1); ?>” name=”s” id=”s” />
<input type=”submit” id=”searchsubmit” value=”Search” class=”btn” />
</div>
</form>

I have since removed this code but site still non-functional.
Deleting cache made no difference.
Any suggestions?