Can not recover a deleted RAID-Z1 volume and data set within a deleted ZFS pool

[mmthabet]

Long story short, i had a ZFS pool of 4 disks (2TB each) setup as RAID-Z1, within that pool i had 1 volume with 1 dataset. It was running initially on a Freenas 7 without problems. Decided to switch to Freenas 8.3.0 which imported the pool without a problem and mounted correctly. Then had problems getting plugins jail to work, during creating new data sets through the GUI for installing the jail system and plugins which didn't go smooth and jail failed to run and then decided to delete the newly made data sets. Doing that, as stupid as it sounds i accidentally deleted my main data set and volume instead of the secondary one. Now i have an Empty ZFS pool.

Being a real noob in open solaris and so, can any one help me to recover the deleted volume and data set within?? as i said its formated as RAIDZ1. Thanks in advance

 

[mmthabet]

Wow, as weird as it gets, i tried many versions of freenas8 then switched to nas4free but still couldn't get the contents of the deleted volume back, so i just re-installed Freenas 8.3.0 and turned off the server over night, and today tried autoimport (again, i tried like 4 times and it failed each time), and voila, it worked and i got my data back. hewwww... Now can anybody explain to me what the heck happened??? and why it just worked this time??