Eclipse IDE - If server option is disable due to some issue

If server option is disable due to some issue when we configure tomcat then..

1. Close Eclipse
2. In {workspace-directory}/.metadata/.plugins/org.eclipse.core.runtime/.settingsdelete the following two files:
   • org.eclipse.wst.server.core.prefs
   • org.eclipse.jst.server.tomcat.core.prefs
3. Restart Eclipse