How to reset if there is no reset button?

[Zakusho]

Router: TL-R402M
Problem: Whenever I access 192.168.1.1 in my address bar I get the following error.

Username or Password is incorrect. Please refer to the troubleshooting below:

Is the "Caps Lock" enabled on your keyboard?
The username and password must be lowercase, please ensure that the "Caps Lock" LED is disabled on your keyboard and try again.

Forgot your username or password?
Please reset the device to the factory default settings if you have forgotten your username or password. The default username and password are both set as "admin".
Note: The settings will be restored to factory default after the resetting.

How to restore the device to the factory default settings?
Firstly locate the reset button on the rear panel of the unit, whilst the device is powered on press and hold the reset button for more than 5 seconds, the device will then reboot and restore itself to the factory default settings.

The actual thing I don't know is how to reset this router if it has no reset button? Oh and to be clear I don't get a pop-up with username and pass where I must type in each respective box. (that error appears instantly)
I tried unplugging my router with no success. I'm running Windows 7 Ultimate Edition now but that also didn't work (at first I was thinking something happened with my previous windows so I changed it)

 

[tigsounds]

The user manual for that device is HERE

 

[Zakusho]

Thanks.