My preview screen is blank when taking a picture with the Canon A550, but I can view pictures in the memory. How can I turn the preview screen back on?

Using the camera:
Your phone has a flash to help you to take pictures in different lighting environments. The flash is on by default, but you can turn it off or use the automatic setting. To set the desired mode when using the camera, select Options > Flash and Flash off, Flash on or Automatic.
Fast viewing with memory card To view your images and video clips quicker, use your memory card as the main memory for storing them.
In the camera application, select Options > Settings > Image / video storage > Memory card.
Capture and send You can send the picture immediately after you have taken it when you are previewing it. To display a picture immediately after you take it, select Options > Settings > Image preview time and the preview time. During the preview time, select Back to take another picture, or Send to send the picture as a multimedia message.
Print your images Your phone supports Nokia XpressPrint to print images that are in .jpg format. To print your pictures, connect your phone to a compatible printer using a data cable or send the image by Bluetooth to a printer supporting Bluetooth technology. Select the image you want to print from the Gallery, and when viewing the picture, select Options > Print.