Hi @Abdulrazapatel1 

When setting up the Range Extender, when you access http://tplinkrepeater.net for the first time, you will be asked to set a web management admin password for the extender.
If you have forgotten that password, the only way would be resetting the extender back to factory default and configure it again from scratch.
Please use a pin to press the reset button on the extender for 1 second to reset it back to factory default.

If you forgot your TP-Link account , please refer to the following troubleshooting:
    1. Tap "Forgot Password" on the Login page.
    2. Please input the registered email address (very important) of your cloud account, and tap "Reset Password", you will receive an email that will guide you to reset the password.
    3. Open your email and click on "Click to Reset Password", it will lead you to a reset password page on our TP-Link cloud website.
    4. Input your new password for your cloud account and confirm, then click "Save".
Or you can reset it through the TP-Link Cloud website: https://community.tp-link.com/en/forgetpw
Note: After 5 consecutive failed login attempts, your account will be locked for 10 minutes. If the account has been locked, you can try the steps above to reset the password.
If you don't have access to your email that is linked with your TP-LINK ID, we suggest you register a new TP-LINK account and bind your device with the new TP-LINK ID.