What's wrong with my code?

I fiddled with my style.css code tried putting in this code to create login button

<?php if (is_user_logged_in()) : ?>
“>Logout
<?php else : ?>
“>Login
<?php endif;?>

I must’ve placed it in the wrong place.
and it it didn’t work (i put it in the are of code below) I deleted it and now my site is down. I probably deleted something important form code below. I cannot do anything. Please Help. Thank you.

#headimg h1 a {
color:#<?php header_textcolor(); ?>;
font-weight:normal;
line-height:60px;
text-decoration:none;
}
<?php endif; ?>
}
endif;

#headimg #desc {
display:none;
}
</style>
<?php
}
endif;