Login error

FTP into your site (or use whatever file management application your host provides) and rename the wp-content/plugins/akismet folder to deactivate Akismet.

That should be fixed in the latest version of the Akismet plugin – 2.5.1 – you can download it from here – https://www.ads-software.com/extend/plugins/akismet/

what happens if i don’t have any FTP and don’t use any of that and I can’t acces my files to deactivate de plugin…
i am unable to log into my site to deactivate this… please help me

If you have no access to the files then you’ll likely need to contact your hosting provider for help to resolve this.