Grey "dust spots" on screen and on pictures

you need to replace the lcd, has a look here.

Do the spots only occur when taking flash pictures and do the spots look like "soap bubbles" and appear in different places in each picture? If so, these are dust particles reflecting the flash back into the lens. It's a problem with all point and shoot cameras because the flash is so close to the lens.

clean the lens,get it serviced the lens as well as CCD.

Those sound like dead pixels as a result of the fall.

You did not mention the model of your camera but I assume its a compact camera.

It happened to me once. I opened the camera, strip the cards and cleaned the lens.

But I warn you, its very annoying operation. You need shakeless hands and super focusing abilities. And also it takes time, need patience. Use mild cleaner not strong one. You may use a hand blower, this method is more simple, dont need to go through lens and strip entire cards etc. Just open the back of the camera and look for a cavity to put nozzle through to lens area and cross your fingers than blow it lightly with hoping the dust gone. :)

Well, not sure if you got it resolved yet but the same thing happened to me. Brought it back and got it fixed under warranty. You'll most likely see more gray circles appear over time. They don't affect the picture but they are annoying.
Cheers
Dan

LCD SCREEN SHOWS FUNCTION BUT NO PICTURE

it should be a stain spot on the camera lens..try taking it to an authorised service point and have it cleaned

I also have a brand new canon powershot sd750, with the SAME PROBLEM!! what IS THIS?!?

Well short answer to your dismanlter question is do not. Contact Canon for a repair cost - this is fine lab work not for the kitchen table.