EC2 Network Error : Connection timeout

You simply need to add an ssh rule for inbound connections to you ec2 instance in the ec2 management console.

1. Go to ec2 console
2. Click Instances on Left
3. Select your instance
4. In the Description tab, locate Security Groups and click the available group link
5. Click edit button on Inbound tab
6. Click Add Rule and select SSH for type, Port Range 22, and Source Anywhere
7. Connect with putty :)

Are you sure you've enabled SSH access in the firewall settings of your instance?

Can you connect with PUTTY to other machines? Perhaps your local firewall is blocking SSH connections.

Also, you cannot simply use a private key you generated with PUTTY - you'll have to create one using the AWS web interface, assign it to your EC2 instance, download it to your local computer and instruct PUTTY to use this when connecting to your EC2 instance.