If you have forgotten the admin password for your Jenkins instance and you are unable to log in, you can try resetting the password using the following steps:

Check if you have access to the Jenkins server file system:

• You will need to have access to the Jenkins server file system to reset the admin password.

• If you do not have access to the Jenkins server file system, you will need to request access from the Jenkins administrator.

Reset the password:

• On the Jenkins server, navigate to the secrets directory in the Jenkins home directory (usually /var/lib/jenkins/secrets).

• In the secrets directory, you will find a file named initialAdminPassword. This file contains the initial admin password for the Jenkins instance.

• Open the initialAdminPassword file and copy the password.

• Go to the Jenkins login page and paste the password into the "Admin password" field.

• Click on the "Continue" button.

• You will be prompted to create a new password for the Jenkins admin user. Enter your new password and click on the "Save" button.

It is important to note that resetting the Jenkins admin password will also reset the passwords of any other users who have forgotten their passwords. You should only reset the password if you are unable to log in and you do not have any other options.