You are going to have to be more specific.
If it has never worked before then you probably need the correct drivers. Download & install them from Canon
Hi it used to work before I rebuilt the pc. When I say it worked, the actual scanning software never worked but I managed to get it to scan by accessing it via device manager but now when I ask it to scan, the printer seems the start the scanning process then the pc freezes and I have re boot the pc to try again.