Do you have logs from the period, when you could access the directory?
If you have, please post them, along with current logs.

Otherwise: It looks like some mainframe system, so see:
Can I connect to a mainframe server? (e.g. VMS, MVS, AS/400)

Hi team! We cannot access the remote directory: 'MPIBP.RTASCF' from any users in Argentina. This file is very important for a process we make in Argentina. We tried to open this file from many different users but we can't access it. It hasn't work for at least a month, before that we could open it. This is the error:

Cannot get real path for '/u/LS0309A/'MPIBP.RTASCF''.
No such file or directory.
Error code: 2
Error message from server: No such file

Please help us!