Problem Update 8.3 to 8.4 or 8.6

[TuTuX]

Hey, i'm french and i have a very bad english !
But i have update my plesk pannel to 8.4 or 8.6 ( i don't remember me )
I have validate the update avec after 4/5 min i have receive a mail this :


The key server refused to update your key.
No further tries will be performed.
Details:

Server response: Key Authorization Problem


And my server is down !!!
When i'm connet to the ssh i have this :
http://www.hostimages.eu/files/2mojimwdynzynkgtd5mq.png

Please help me, i have 380GB of files because i'm a french hoster of file !

Thanks for your help.