Sometimes you create a virtual machine without any intention of putting it on a Virtual Network (Vnet) , and suddenly you want to make this machine Join your Vnet on you windows Azure subscription.
This is a step by step guide on how to do this:
1. First you delete the Virtual Machine by clicking on Delete in the lower task bar in the Azure management portal
2. A warning message will be displayed as the screenshot informing you that the VHD won’t be deleted and that we are only deleting the VM itself, click Yes
3. Go ahead and create a new VM and choose from Gallery and click on My disks where you will find you the disk of the machine that you have deleted residing their, choose and clicknext and complete the until you reach the Virtual network page where you will be able to add you machine to a virtual network if it is in the same region as the storage account hosting your VM.
4. After this finishes, you will get your VM with an internal IP form your Vnet.