i reloaded windows on my laptop and i am using my blackberry 9700 as a modem,however my internet icon does not work.when trying to connect to the internet,a message box appears with the words "error "on it.
Your service providor for the Blackberry will have some tethering sofware available, VZAccess for Verizon, Sprint Connection Manager (old name for that I think), etc...
You probably had this program on your laptop before you re-installed Windows.
Another way of doing this is to setup a new Modem connection in Windows and use the configuration provided by your phone vendor to configure it. But you will still need the proper drivers for your phone on the computer for it to see it as a modem.