no access to config page

First of all; I apologize for being a newb. I've searched and searched and I'm having no luck. My config page is no longer accesible, modem is connected directly to pc. No coax. I've gone and tried to change through tcp settings and still no luck. If I can get to config page (192.168.100.1) I'm sure I can fix it. Any thoughts would be greatly appreciated.
Thanks for your patience, and understanding .. ....
I do not mean to disrespect so if I do I apologize.
Tiggity