get rid of the arrow in previous_post_link?

Just copy your next_post_link:

 <?php previous_post_link( '%link', '' . $prevthumbnail . '' ); ?>

Per the codex page, the first parameter specifies what will we be shown (thanks Chip!)

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)