How do I reset a Canon A85 camera back to default values?

This sounds like it might be a defective CCD imager, and is a known defect for your particular model camera.. If so, Canon should fix this for you for free if you live in the US, Canada, and a select few other countries. If you live outside the US, contact Canon support for your country to see if they'll still honor the advisory (some still will, especially if you stress you knowledge that this is a known defect of the camera). They may also include free shipping both ways (free shipping varies with countries). This is regardless of your camera's warranty status. Please see this link for more info.

Affected cameras with this problem include: A60, A70, A75, A80, A85, A95, A300, A310, S1 IS, S60, S230, S400, S410, S500, SD100, SD110, IXUS V2/V3/300/400/430/500/II/IIs, IXY Digital 200a/300a/320/400/450/500/30/30a

you can cycle the display to off, on and an info screen. look for the display control on the back of the camera..it may be in the menu on the a85, but it's designed to turn off the display for certain situations. If you cycle thru and the display still doesn't work, you may have a larger issue and and A85 doesn't hold alot of value for repair... check your display setting first...

If your Canon A85 shows distorted image in live view (camera mode) then its known problem of ccd imager chip failure. Check below image.
canon offers free of cost ccd imager chip replacement in A85 model.
Please confirm if its canon A85 camera or any other model to provide you more info.

It is problem of bad CCD Imager in your Canon A85 camera and ccd imager will be replaced to get correct picture in live view/ shooting mode.
Canon will repair your camera free of cost. Click Canon CCD Imager Advisory for details.
Thanks.

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 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

Its is bad ccd imager known problem in Canon A85 camera.
Canon will repair A85 free of cost in ccd imager problem.
Click Canon CCD Imager Advisory for details.

Its problem of bad ccd imager in your camera and ccd imager will be replaced.
Canon will repair Free of Cost for bad ccd imager as per announced scheme.
Click Canon CCD Imager Advisory for details.

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

Your zoom probably does not come out all the way and therefore you get some blurry shots. Had the same problem on a Panasonic camera. Solution: replace zoom motor and gears. Results=expensive. Goes beyond the value of the camera. You might want to buy another used A85 or newer digital camera.

To reset your camera back to the original settings, please switch ON your camera and press (keep it pressed) the MENU button for 10 seconds. You will be asked to "reset settings to default". press the left/right buttons and select OK