You have many options to restart Jenkins manually, but mainly two (URL or command line):
Alternative 1: Using the Jenkins installation URL:
Jenkins_URL/restart.
Example: http://jenkinsserver.com/restart
This type of restart forces a restart without waiting for builds to complete.
If you need to wait for the jobs endings you can use:
Jenkins_URL/safeRestart.
Example: http://jenkinsserver.com/safeRestart
Alternative 2: Using the command line, depending on your Jenkins installation.
If you're installing using rpm or deb package or you have the Jenkins installation in Red Hat, Ubuntu, or Debian, you can use these commands:
sudo service jenkins restart
This restart Jenkins in one step.
sudo service jenkins stop and sudo service jenkins start,
This restart Jenkins in two steeps.
Note: if you need to check the Jenkins status, you can use this command: sudo service jenkins status
If you are using CentOS, you can use this command:
sudo systemctl restart jenkins
Note: if you need to check the Jenkins status, you can use this command: sudo systemctl status Jenkins
