Dear friends,
I have LG Google Nexus 5 (Hammerhead D821(H) 32GB) model. Some days ago I tried to install Ubuntu Touch OS through UBports Software in my nexus 5 phone. But I forgot to enable USB Debugging first. So when I started the flash process and try to unlock bootloader, one time it show lock state unlocked. But In reality it was not unlocked. Because of this reason Ubuntu Touch OS installation is not completed and it corrupted my phone. Now I am unable to boot in android also. I also tried to re-flash my phone with Google Factory image but it was not completed because of my bootloader is locked. I don't know how i can unlock bootloader now. I used Wipe Data & Factory Reset option in Recovery Mode but it is also vain. I also used ADB sideload to install android os but again vain. Please help me how can I correct my phone and become again able to install Ubuntu Touch.

@Rondarius Dear Sir I tried it already. I downloaded the factory image from google developer website, unlock the bootloader, and run the command flash-all.sh but installation stopped because of bootloader unlock problem. Because in reality bootloader didn't unlocked it only show unlocked. If I restart the bootloader it again shows in locked state.

@Rondarius Respected sir the above said factory image installation needs bootloader unlocked & my phones bootloader is locked and my phone is corrupted also. So I can't enable USB debugging and without USB debugging it is not possible to unlock bootloader.

@Rondarius The installation process stopped and below error shown through picture came.

@Lakotaubp I also used it. One its show unlocked but after rebooting bootloader its again locked.

if I use sudo adb sideload command this errors show

@Lakotaubp I did it. its unlock bootloader but when I reboot bootloader its again show state locked.

@Lakotaubp Yes "sudo fastboot devices" command show the fastboot device is connected to my ubuntu pc.

@stanwood Dear sir I try many times "sudo fastboot oem unlock" command in my Ubuntu PC but one time its show unlocked but again it shows unlocked after rebooting bootloader.

@joe Dear sir I try many times "sudo fastboot oem unlock" command in my Ubuntu PC but one time its show unlocked but again it shows unlocked after rebooting bootloader.

I tried it. But OEM is not unlocking because I didn't on USB Debugging as I said in my post.