Hi,
After reverting to pogoplug OS, remove the USB stick and reboot the Pogoplug.
Go to
https://my.pogoplug.com and check if it is still there, if not try to register it again.
If it is there, make shure SSH access is activated and re-enter a password.
Check DHCP table on your router to find the IP address of the Pogoplug.
Try to SSH the Pogoplug.