Is your problem that the router is not accessible at the expected IP address or that you cannot find the default account/password?
If the former, reset the router to factory default settings, connect a PC by ethernet, and show ...
Open a (black) Command Prompt window:
Hold the Windows logo key and press r; in the Run box type cmd and click on OK.
Type the following command:
IPCONFIG /ALL
[Note that there is no space between the slash and ALL.]
[Press ENTER after each command.]
Right click in the command window and choose Select All, then hit Enter.
Paste the results in a message here.
If necessary use a text file and removable media to copy the results to a computer with internet access.
If the former, reset the router to factory default settings, connect a PC by ethernet, and show ...
Open a (black) Command Prompt window:
Hold the Windows logo key and press r; in the Run box type cmd and click on OK.
Type the following command:
IPCONFIG /ALL
[Note that there is no space between the slash and ALL.]
[Press ENTER after each command.]
Right click in the command window and choose Select All, then hit Enter.
Paste the results in a message here.
If necessary use a text file and removable media to copy the results to a computer with internet access.