Why did my camera stop taking pictures and I have a big red ! showing on my app

verify that the memory card isn't full or missing.

Go to this site and download a free copy of your user manual. It should tell you how to operate your camera: https://support.nikonusa.com/app/answers/detail/a_id/16311/~/users-manual---coolpix-l100

Any scratches on any mirrors should NOT show up in the pictures, since there are no mirrors in the light path when taking pictures.

The big angled mirror you see when changing lenses flips up out of the way when you take a picture (that's the 'R' in "SLR"). Scratches on it may affect the focusing and exposure metering but will not show up in the pictures.

Yes you have the incorrect setting the 1/15 in red is showing you the shutter speed and if you are hand holding this and composing/shooting using the LCD screen there is no way on this earth you are going to have a sharp image. The F50 (I think this is far beyond the capabilities of this camera) is showing you the aperture F32 might be more realistic but none the less the aperture is closed way down to maximum stop down. Until you understand your camera more I'd suggest switching to the "Auto" mode it's a little camera icon and that way two things will happen. First you will get a picture and second the more you use it the more familiar you will become with it.
Also I hope you purchase a Memory card, your camera takes the SD type, make sure the card lock is in the correct position see diagram and that you format the new card check your manual for formatting instructions. Read your manual and go make some great pictures.
Diagram
Little circle show correct position for storing new pictures on the CD card

through it

Red light indicates that the camera is out of charged., Try to charged your battery for 3-4 hrs if you encounter flashing red on a fully charged battery you need to call kodak 1 800 235 6325 ext 12

You can charged you camera using 5V AC Adaptor or a USB cable taht attached into the computer

Your lens may need adjusting. This info may help . Other People solved problem. Lots of Info on this link.

http://www.fixya.com/support/t102982-e_18_problem

you need to download the pictures off the camera. Once they are downloaded and erased from the camera, you'll be able to take pictures again.

Your camera jumped out of gear. Open the front metal cover and disassemble all arm working with the main motor gear and try to reposition the red dot on the big gear with the small gear side by side. Presto now your camera is aligned. Place all arms back in order to your new alignment.you got your self a working camera. D: 3403 3404 mean error = some thing is block your lense and stopping the motored gear. For future referance don't drop the camera agian, next time it might be a expensive fix next time around.

You should check and see if the red tube is showing any light. The green and blue make yellow when the red tube stops working. If it is showing red but looks dull, you will need to change out the fluid inside the tubes, as it is corroded. I will post a fluid change procedure on the repair tip for this set. I cannot post it here as they will not let me. They say it is too long. Go figure. They do not let you post what you want I guess.. Good luck with your repair.