Zyxel Prestige 643 Modem Can't Login !!!!!

Hello,

I cant seem to connect to my router through my browser.  It is the ip number 192.168.1.1  which is the default to login to the router configuration.  I need to make some changes but I can't!  I changed an option in the remote management control screen.  I put enable under web server, I changed the port from 80 to 5500, and put the IP which I want to be accessed.  It then tells me to restart and now I can't login to the modem by the default ip number mentioned above.  I know which setting now to change to run my server but I can't login anymore!  Can anyone please help me.

Thanks,

Geo