Don't understand. Please give more details.
Is the zpool on the same disk as the OS? Is the disk with the zpool still OK and available? If the OS disk and the zpool share the same disk (or you are using root-on-ZFS), how did you install?
As an example: My server has a small SSD for the root file system, and two spinning disks for a (mirrored) ZFS pool for the home directories, and a few smaller things. I reinstalled the OS by creating a new root disk (on a new SSD), then physically replaced the old SSD with the new SSD, and my zpool simply worked after doing a "zpool import"; I had already done "zpool export" before shutting the old version down.