When the camera is turned on, the display shows all symbols, but can't see any image.

If these pictures were edited on your PC and the card placed back into the camera, then this is the issue and your camera can no longer read the image file. Some programs will change the structure of the file and that's why you may be having difficulties.

Usually the photo is displayed for a short period of time. Try the setup in the menu. There should be an option for previewing recent pictures.

I presume you're asking about a Digital Rebel and not a 35mm film Rebel (as per the question heading).

If so, that's probably normal. It's only relatively recent dSLR models which have a "live preview" facility (often wrongly called "live view"). The whole point of an SLR is that the viewfinder is the main compositional viewing tool; the LCD is there solely to display and adjust camera functions and to review images already captured.

Most current and recent SLR's now have live preview, and all true SLR's are incapable of viewing the image at the actual moment of image capture as the viewfinder mirror must flip up out of the way of the image sensor.

If you want live preview then you must change your camera. if you tend not to use the viewfinder anyway then consider mirrorless Compact System Cameras such as the Olympus and Panasonic Micro Four Thirds models as they do have a true live view capability and the LCD is the main (or only) tool for composing images. Panasonic also have their regular Four Thirds G range, which look like an SLR but have an electronic viewfinder and they are also capable of true live view.

when you are in the playback mode, you can use the zoom function (as you use it when you take a picture), this will zoom into the image you took.

the yellow frame show you where you are in the full image.

Sounds like they accidentally pressed the DISP or DISPLAY button on the back of the camera. This manually turns the screen on and off to save batteries. You would then use the optical viewfinder in its place. To turn the screen back on, just press the DISP button one more time with the camera turned on.

Either shutter jammed or CCD is gone bad.
Use warranty.

Pentax K100D does not have Live View function. So you can't preview the image before taking the image.

There is usually a button for turning the screen on and off, or only on for previewing (browsing images). (and sometimes there is an option for having the screen on without the On-Screen Display)

I don't know exactly which one on your camera... sometimes the up button, sometimes there is a little symbol.

Play with it, and eventually you'll find the right button. =-]

Try pressing the up or down navigational button, that will change the preview mode.

Sounds like you might have accidentally turned the display off. Turn on the camera and press the DISP button once on the back of your camera.