If you have access to script console can disable all jobs with

import hudson.model.*

disableChildren(Hudson.instance.items)

def disableChildren(items) {
  for (item in items) {
    if (item.class.canonicalName) {
      if (item.class.canonicalName == 'com.cloudbees.hudson.plugins.folder.Folder') {
          disableChildren(((com.cloudbees.hudson.plugins.folder.Folder) item).getItems())
      } else if (item.class.canonicalName != 'org.jenkinsci.plugins.workflow.job.WorkflowJob') {
        item.disabled=true
        item.save()
        println("DISABLED: ${item.name}")
      }
    }
  }
}