Oracle OEM died

Problem:
I only changed my Oracle server's IP or hostname and the whole Oracle Enterprise Manager thing died on me!

Solution:
Oracle OEM depends on the IP and Hostname that is during the installation. So if its changed, things will go wrong.

Soln:

Perform the following steps.
1) Run the following, this will remove entire OEM setup from Oracle
emca -deconfig dbcontrol db -repos drop

2) RUn the following, this will remove the orphaned OEM console service
sc delete consoleServiceName

3) Remove the existing listener with Net Configuration Assistant.

4) Change listener.ora and tnsnames.ora to fit the current IP and hostname settings.

5) Restart the remaining oracle services. (Restart comp if not sure)

6) Add new listeneer with Net Config Assistant

7) Ensure Listener and Database instance are up
Run the following, this will reinstall the entire OEM setup for oracle.
emca -config dbcontrol db -repos create


8) Open the Enterprise Manager Console and try again