Removing previous installation of Oracle from Windows box

Suppose you have deleted folders of previous Oracle installation from your Windows box. Now you run Oracle installer to install Oracle again, but the installer is saying that Oracle is installed and asks you whether you want to uninstall (deinstall) that. You choose to unistall previous Oracle installation, but fail to find one and ultimately fail to install Oracle anew.

If you are facing this problem, then you should think of stopping Oracle-related services and remove Oracle-related registry entries. To know how to do this, follow this:

• Stop Oracle-related processes and services. Steps are:

1. Run Task Manager and go to Processes tab of that.
2. Now look for services with names containg ora or oracle.
3. End those processes.

• Delete Oracle installation folder.

1. If you could not have deleted C:\oracle or D:\oracle or wherever you had installed Oracle previously and C:\Program files\Oracle, then try deleting that folder now.

• Remove Oracle-related registry entries.

1. Start --> Run --> type in regedit and hit OK.
2. Delete the following keys (some may have slightly different names in your registry):
   HKEY_CURRENT_USER\SOFTWARE\ORACLE
   HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EventLog\Application\Oracle.oracle
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\OracleDBConsole
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Oracle10g_home
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\OraclService

Now restart your computer and try installing Oracle afresh.

Enjoy!!!