Locked Out (wp-admin) 1.5.2

I’ve just upgraded WordPress to 1.5.2 using a “gadget” called “Installatron” (obviously I should have done this manually in hindsight.)
Everything seemed ok (as it has in the past) except now I can’t add a file to “wp-admin” folder (it was the only file I can tell that was removed in the upgrade), I have tried via FTP (permission denied) and also through the file manager in “DirectAdmin” (permission also denied), I am unable to change permissions via FTP or DirectAdmin, the latter tells me the folder is assigned to “root” which , as the administrator I pretty much figured that was me, evidently it’s not it’s whoever is sat there wearing the Apache baseball cap.

The file I’m trying to upload is “options-pxsmail.php” (a great plugin by the way).

Anyone else locked out since upgrade time?