Can not access to wp-admin

Hello!

Since a week ago I’ve had several problems in my website http://www.astroemporda.net. First, only appears header, but I desactivated plugins via FTP. Website works fine, but I could not access to wp-admin (error 500).

Today I’ve recovered a database buckup (from a wp plugin) and wbsite works fine, but I can not still access to wp-admin. I can access to all pages, including wp-login, but when I try to access with my username and password error 500 comes back.

Can anyone help me? Is urgent!!

Thank you very much!