Cluster partly not functional, how to restart

In one of my 3 clusters the Tasklist became unresponsive, so in a first step I killed all running processes , but it did not come up again.
Next step was an update to the latest version, but here similar issues. everything is updated except the part of the tasklist, which is still “Updating” since 3 hours…
Is there any way to restart a cluster manually, complete or partly?