Start with the
Troubleshooting Guide - possible causes and suggested solution can be found in this manual.
If this does not help, Google the error code and include O/S and NBU version as a lot of problems are O/S specific.
Status 13 and 14 are most of the time network related as well (although the error description says file read/write failure) - see In-Depth Troubleshooting Guide for these two status codes:
ftp://exftpp.symantec.com/pub/support/products/NetBackup_Enterprise_Server/276941.pdf
ftp://exftpp.symantec.com/pub/support/products/NetBackup_Enterprise_Server/278568.pdf
TechNotes dealing with Status 24 on Windows:
http://seer.entsupport.symantec.com/docs/296341.htm
http://seer.entsupport.symantec.com/docs/304578.htm
Status 83 and 84 are media/device related and are normally caused by the same underlying problems.
In-Depth Troubleshooting Guide for Status 84:
ftp://exftpp.symantec.com/pub/support/products/NetBackup_Enterprise_Server/273908.pdf
Consider the following important note in above TN:
As an application, NetBackup has no direct access to a device, instead relying on the operating system (OS) to handle any communication with the device. This means that during a write operation NetBackup asks the OS to write to the device and report back the success or failure of that operation. If there is a failure,
NetBackup will merely report that a failure occurred, and
any troubleshooting should start at the OS level. If the OS is unable to perform the write, there are three likely causes; OS configuration, a problem on the SCSI path, or a problem with the device.