@kamibhaaya55426 

For your case, here are some suggestions. 

Could you please let us what kind of password do you mean?
1. If you mean the login password of your TP-Link device, it is suggested for you to use admin in lower case to check. However, if admin cannot work, please reset your TP-Link device to default settings by pressing and holding the reset button for 10s. 
2. If you mean the password of your TP-Link ID, please reset the password on the following web link:
https://www.tplinkcloud.com/forgotpassword.php

3. If you mean the WiFi password of your TP-Link device:
if your device is a range extender, please use the wifi password of your main router to have a try and it should be exactly the same as your main router.
if your device is a TP-Link router, it is suggested for you to use the default wifi password to see if it works. The default wifi password is printed on the label of this device itself as wireless password/PIN. If the default password doesn't work, please reset your device and have a try again.