SAP MMC Issue: systems desappear after installing ONE instance

I encounter the following problem:

after uninstalling a sap instance which didn´t work properly, the remaining systems are not shown in the sap mmc anymore. (although i didn t uninstall them. the files , folders of the systems are still there).

How can i make the sap mmc show me all available systems again?

Message was edited by: Gideon Lenz