This is a simple procedure built in to windows to let you know if your modem
is responding, or if it may be dead.
Double click on "My Computer", then double click on "Control Panel".
Double click on "Modems".
You should see a windows that shows all (if any) of your modems on your machine.
(If you have several listed, but only one modem on your machine, then you need to remove
all but the one that is in the machine. If you don't know which one, then remove
all of them and restart your computer. Windows should find it (if it is still functioning) and install it.
Go back into "Modems".
At the top of the window, click the "Diagnostics" tab. Click the com port that is next to your modem on the list. Now hit the "More info" button. A window should come up with several AT commands in it. This will let you know that the modem is responding, and that windows can recognize it.
If you get anything else, including a blank screen, then your modem is probably not installed correctly, is failing, or is already dead.
Your computer might need to be be serviced.
The AT commands that you see do not necessarily mean that the modem is completely working, or that the CORRECT drivers are installed, but it will at least give you an idea whether or not Windows is recognizing it. Be sure to close all the windows before you try to connect.