This is the official page, where you will find the Official Vivo Stock Firmware ROM (Flash File). The Firmware comes in a zip package and contains USB Driver, Flash File, How to Flash Manual.
Vivo Y21 PD1309W Firmware (Stock ROM)
The Vivo Firmware helps you to downgrade or upgrade the Stock Firmware of your Vivo Smartphone, FeaturePhone and Tablets. It also allows you to fix any IMEI related issue, Software related issue, bootloop issue.
Package Name: Vivo_Y21_PD1309W_EX_B_5.3.11_09252012_OTA.zip
How to Flash: Copy update.zip file to hone SD and flash it from the recovery menu.
Package Size: 822 MB
How to Flash Vivo Y21 PD1309W Firmware (Stock ROM)
Step 1: Download and Extract the Vivo Y21 PD1309W Firmware Package on the Computer.
Step 2: Once you have successfully extracted the firmware Package, you will be able to get the Flash File, Driver and How-to Flash Manual.
Step 3: Now, Install the provided USB Driver on the Computer.
Step 4: Once you have successfully installed the USB Driver, Copy the update.zip package to the phone SD memory.
Step 5: Once you have successfully copied the update.zip package to the Phone SD memory, you need to disconnect your device from the computer.
Step 6: After disconnecting the device, You need to boot you device into the recovery menu.
Step 7: Your your device is booted into the recovery Menu, locate the update.zip package.
Step 8: Once you have located the update.zip package, you can flash it using the recovery option.
[*] Backup: We recommend you to take a backup of your personal data from the device, before flashing or writing the Stock Firmware or IMEI because flashing the stock firmware or IMEI may permanently delete your personal data from the device.
[*] Original firmware: The above Vivo firmware is the original firmware, released by the Vivo Mobility Inc. We have scanned the firmware with Eset Internet Security before publishing it online.