How To Root HTC Desire 820 smartphone
Step 1 : To get started, download TWRP recovery and SuperSU to your computer. Once done, connect your smartphone to the computer and transfer the SuperSU file to your device’s SD card and disconnect your device from the computer.
Step 2 : Now, extract the TWRP recovery zip file into a folder. Once done, switch off your device and boot into the FASTBOOT mode by pressing Volume Down and Power Key simultaneously. Once your device is in FASTBOOT mode, connect it with the computer by using original USB data cable.
Step 3 : Next, open the folder where you have extracted the recovery files and click on flash-recovery.bat. This will start the recovery flashing process and once it is done, boot into the recovery mode by using the Volume Keys and Power button.
Step 4 : Now, select “Install” and choose the SuperSU zip file that you transferred to the SD card of your device in Step 1 to begin the installation process. Once it is done, reboot your device normally.
Done . goodluck.