Use this video to create a new root password on devices running Junos OS.
If your device is running a different version of Junos, follow one of these procedures instead:
How to Recover the Root Password in Junos OS Evolved: https://www.youtube.com/watch?v=6jtHLv2Xfw0
How to Recover the Root Password in Junos OS with Upgraded FreeBSD:
Learn more about password recovery for Junos OS at the Juniper Networks TechLibrary: Recovering Root Password https://www.juniper.net/documentation/en_US/junos/topics/topic-map/recovering-root-password.html