How do i reactivate pluggins through ftp??
You can't. Once a plugin is flagged as deactivated in the database (because it's not there for example) then you need to get the WordPress dashboard working to re-activate it.
And if im not using a theme wont i loose my work if i change to a theme??
You should not lose any work but if you're really concerned about that make a full file and database backup before doing anything else.
This works (sort of)
But all of the
wp-admin references are broken. Either you have something is blocking that via some server restriction or
.htaccess or that directory has been deleted.
It looks like you have WordPress 3.5 so download that release and re-upload the
/wp-admin directory only.
See if that works.