Pages, Comments, Entries gets 404

After my domain got hacked not once but twice, I decided to switch to a brand new account since they have guessed my account username. However, that proved to be a problem moving my old archive databases over to the new account.

The main index looks okay. However, I can’t click to any of my pages, posts, categories or comments as I get the 404 page.

Furthermore, when I edit my pages, under Page Options, there’s this error note:

Warning: file(/home/username/public_html/wp-content/themes/blix/comments-popup.php): failed to open stream: Permission denied in /home/username/public_html/wp-admin/admin-functions.php on line 631

Warning: implode(): Bad arguments. in /home/username/public_html/wp-admin/admin-functions.php on line 631

What does it mean and is this affecting my links?

Urgent help would be greatly appreciated!