I recommend you check all the storages of the nodes for the presence of disks related to VMID 103. If you cannot find a disk it is enough to restore the backup, this will recreate the disks and configuration as stored in the backup. You can also restore to a different VMID, if you do not want to overwrite the current VM.
See also
https://pve.proxmox.com/pve-docs/pve-admin-guide.html#chapter_vzdump
