This article will explain root password recovery on PTX evo platforms. 

If you forget the root password, use the password recovery procedure to reset the root password.

To recover the root password, perform the following steps:

1. Power off the router by pressing the Power button on the front panel.
2. Have direct console access to the device then wait until you get GNU GRUB option as displayed below.
3. Quickly select 'Primary [Recovery password]' using the down arrow key and press Enter to enter recovery mode.

             GNU GRUB  version 2.02~juniper/rel_v3~

 +----------------------------------------------------------------------------+
 | Primary junos-evo-install-ptx-fixed-x86-64-21.4R3.13-EVO                   |
 |*Primary [Recover password]     <<<<<<<<<<<<<<<<<<<<<<<<<<                  |
 | Primary [Debug System]                                                     |
 | Snapshot junos-evo-install-ptx-fixed-x86-64-21.4R3.13-EVO                  |
 | Snapshot [Recover password]                                                |
 |                                                                            |
 |                                                                            |
 |                                                                            |
 |                                                                            |
 |                                                                            |
 |                                                                            |
 +----------------------------------------------------------------------------+

      Use the ^ and v keys to select which entry is highlighted.
      Press enter to boot the selected OS, `e' to edit the commands
      before booting or `c' for a command-line. ESC to return
      previous menu.
   The highlighted entry will be executed automatically in 3s.

   4. The system will now display a prompt for you to enter the new root password.

Disk boot ...
IMA is 1
Loading kernel ...ok.
loading devicetree bzImage-ptx1000-rcb.dtb ...ok.
Loading initrd ...ok.
Booting ...
System is running with minimal count of software versions
Installing kexec kernel...Cannot get kernel page_offset_base symbol address
done


===============================
Password recovery in progress
===============================
New password:
Retype new password:
passwd: password updated successfully
Password recovery done

Welcome to Linux!

[  OK  ] Listening on udev Control Socket.
[  OK  ] Started Dispatch Password Requests to Console Directory Watch.
[  OK  ] Listening on /dev/initctl Compatibility Named Pipe.
[  OK  ] Started Load Kernel Modules.
         Mounting FUSE Control File System...
         Starting Apply Kernel Variables...
         Starting udev Coldplug all Devices...
[  OK  ] Started Self Monitoring and Reporting Technology (SMART) Daemon.
         Starting Zookeeper Server...
[  OK  ] Started Arp filtering arptables.
[  OK  ] Started Zookeeper Server.
         Starting MGD initialization of schema and database...

Juniper Linux Distribution 2.2.1 jtac-ptx10003-80c-r2007 ttyS0


jtac-ptx10003-80c-r2007 login:

   5. You can now access the system using the new root password.