how restore my hard disk with partion table destroyed by AirPort upgrade?

After the 7.3.1 upgrade my AirPort have destroyed the partion table of my hardisk. 500 gb of veyi important data.

I nave plugged the HD in my mbp and with utility disk i see 0 partion. I think Airport haven't erased all data but only destroyed partion table.

The HD was an HFS+ with many many important file.



Its incredible what happened with only a firmware upgrade