Hello Alvin, go to the control panel and right click modem, then go to properties and you should be able to change the port.
Alternatively go to the device manager and have a look at the ports that are listed.
Or go into your bios and see what ports are listed as enabled/disabled.
You could also try uninstalling the modem and then re-installing, the port should be assigned automatically, but if this caused the problem in the first place it might not help.
Here are a couple of programs that you might find useful:- COM-Control (zip), from SCHNEIDER-IT - Free Downloads on ZDNet | Shareware, Trialware, Evaluation Software Advanced COM Port Redirector (exe), from Eltima Software - Free Downloads on ZDNet | Shareware, Trialware, Evaluation Software
If you are not sure what to do, post the details and we'll fix the problem.