Some times, upon rebooting your computer, Websphere (Network Deployment) will start but the node agent won't. The node agent is responsible for spawning and killing server processes and also responsible for configuration synchronization between the Deployment Manager and the Node. None of the distributed products would work if the node agent isn't up. You will not be able to start the node agent from the Websphere Admin Console GUI. You will have to start it from the command line utility.
1. Open up a Command Prompt as an administrator (right-click -> Run as administrator)
2. Navigate to you Websphere server bin directory: ie C:/Program Files/IBM/Websphere/profile2/profiles/AppSrv01/bin
3. Run startNode.bat
4. You should see the confirmation saying "node agent is open for e-business".
5. Now log back into the WAS Admin Console. Click on "System Administration" -> node agents -> refresh the status. You should see a green arrow upon refresh.
6. Now you can start your cluster or server by clicking on "Servers" on the left panel