I have created a virtual machine instance from snapshot taken the production server. SSH key is set. But I am unable to ssh into instance both from the putty and google clou
It seems the issue here is that the network interface of your new instance is not coming up. You can try one of two steps:
1) try connecting through the serial console. This does not connect through port 22 or use SSH. However, if the network card is not coming up at all, this may also fail.
2) Add a startup script to the instance which will run the commands you need to configure the network card