Please follow the link below and select
Wireless product
Model number to match your router.
http://www.tp-link.com/en/support/download/
Download the firware to your pc.
INCORRECT FIRMWARE VERSION WILL KILL THE ROUTER, PLEASE MAKE SURE YOU HAVE THE CORRECT VERSION FOR YOUR ROUTER.
Step 1 Open the web browser and type the IP address of the wireless router (default is 192.168.0.1) into the address bar and then Press Enter.
Step 2 Type the username and password in the login page, the default username and password are both admin.
Step 3 Select System Tools->Firmware on the left side, then click Browse.
Step 4 Locate and select the correct firmware file for the router you have saved to your pc, click OK.
Step 5 Click Upgrade button to start upgrade, wait for a few minutes till the upgrade complete and the router reboot.