Screen has gone white

This appears to be a deeper problem than can be fixed with advice on here. I suggest you take it for a professional repair. Check the repair estimate with the value of the camera.

This is what I want to say. On a Canon camera, always press the display button several times, to cycle through all possible screen options. Including the display nothing.
Try this in the recording and in the view mode just to get used to what it does.

The LCD screen inverter maybe faulty. Take your camera to the Canon repairer to have the camera fixed.

Don't fret, you still got a bargain at that sale. This sounds like it might be a defective CCD imager. If so, Canon will fix this for you for free, including free shipping both ways. This is regardless of your camera's warranty status (including whether you bought it used or new). Please check this link for more info.

Applicable cameras include:
A40, A60, A70, A75, A80, A85, A95, A300, A310, S1 IS, S60, S200, S230, S330, S400, S410, S500, SD100, SD110, IXUS V2/300/400/430/500, IXY Digital 30/30a/200a/300a/D320/400/ 450/500

This sounds like it might be a defective CCD imager. If so, Canon should fix this for you for free, including free shipping both ways. This is regardless of your camera's warranty status. Please check the following two links for more info:
　
http://camerarepair.blogspot.com/2007/11/canon-digital-cameras-showing-black.html
　
http://www.usa.canon.com/consumer/controller?act=PgComSmModDisplayAct&fcategoryid=225&modelid=13390&keycode=2112&id=29819
　
Applicable cameras include:
A40, A60, A70, A75, A80, A85, A95, A300, A310, S1 IS, S60, S200, S230, S330, S400, S410, S500, SD100, SD110, IXUS V2/300/400/430/500, IXY Digital 200a/300a/400/450/500

Did you accidentally press the DISP button on the back of your camera? This manually turns the screen on and off to save batteries. Try pressing this button one more time to see if it turns the screen back on.

This sounds like it might be a defective CCD imager. If so, Canon should fix this for you for free, including free shipping both ways. This is regardless of your camera's warranty status. Please check the following two links for more info:

http://camerarepair.blogspot.com/2007/11/canon-digital-cameras-showing-black.html

http://www.usa.canon.com/consumer/controller?act=PgComSmModDisplayAct&fcategoryid=225&modelid=13390&keycode=2112&id=29819

Applicable cameras include:
A40, A60, A70, A75, A80, A85, A95, A300, A310, S1 IS, S60, S200, S230, S330, S400, S410, S500, SD100, SD110, IXUS V2/300/400/430/500, IXY Digital 200a/300a/400/450/500

does it give you a lens error? are the shutter closed?
It is either the lens or the CCD.

Sounds like a defective CCD imager. You may be in luck. Canon should fix this for you for free, including free shipping both ways. Please check the following two links for more info:
http://camerarepair.blogspot.com/2007/11/canon-digital-cameras-showing-black.html
http://www.usa.canon.com/consumer/controller?act=PgComSmModDisplayAct&fcategoryid=225&modelid=13390&keycode=2112&id=29819
Applicable cameras include:
A40, A60, A70, A75, A80, A85, A95, A300, A310, S1 IS, S60, S200, S230, S330, S400, S410, S500, SD100, SD110

Have you checked the display mode you're in? If you have the display set to off (to save power) and also the picture review time set to off, then you'll just see a black screen. Try pressing the 'Disp.' button below the screen when the camera is on - it should cycle through different settings with each press: Off, On, On with picture info. Similarly, in the playback mode this will show you more or less info about the picture you are viewing.

Even if the display is switched off, if you have your 'review' option in the menu set to anything other than Off (i.e. 2 seconds), then you should see the picture you've taken appear on the screen straight after taking it.

If it's not that, then I don't know the answer....