Messages stuck in delivering status

Hi all,
I have an idoc-xi-ftp scenario with EO quality of service. For the very first tests we set up a file CC using nfs and everything worked fine.
Today I received the info to connect to the FTP server and introduce it on the file CC. The issue comes because some kind of problem writing on the ftp server leaves the messages in status "delivering" (DLNG).  While FTP guys try to fix the issue (they don't know where he tissue is right now) I have switch again to NFS with the old configuration in order to allow the users to keep testing.
But the issue comes because now the messages being sent to NFS scenario are marked as to be delivered and they are not processed.
I'm suspicious about the delivering ones and I'd like to cancel, but the cancel button doesn't allow me to do it so I'm hanged in a circle.
Any ideas?
Thanks in advance,
David R.

Yes, ABAP +Java implies a complete restart of the PI server, which is not recommended in the production environment.
Generally, this case is like a deadlock situation. We will not be able to either resend/cancel the messages in delivering.
So , best option would be to identify which server node these messages are stuck and then restart that server node.
With the server node restart these messages in Delivering are again reprocessed by the server.