Why does my canon eos rebel t3 not take a picture when the shutter button is depressed but tje red eye reduction button keeps flashing and the video still works?

Try resetting your custom menus...

yes..that's a twitchy button all right..can you inspect it to see if there's any accumulated dirt/grease can cause it to actually 'stick'

Have you tried cleaning the contacts on the lens/camera?
Is the lens free from obstructions?

Puzzling??? but remove battery and turn off red eye reduction after reinstalling battery. Rich

Do the pictures come out properly? It's normal for the flash to emit a couple of pre-flashes so that the camera can properly set the exposure. Also, if you have red-eye reduction turned on, the flash will fire several times to get pupils to contract.

i try to write protect my pictures on my camera canon eos rebel t3 after that i cant snap i cant do anything when i press the shutter button then it write cards write protect switch is set to lock please help me

Red eye is caused by two things, the iris of the eye not prepared for the gobs of light that happens when someone is in the dark and also the fact the in-built flash is on a very close axis to the lens.

There is very little you can do except buy a SpeedLight like a 430EX or a 580EX to get the flash higher than the camera and it gives you opportunity to bounch the flash off surfaces like a ceiling or a wall.

The other is to get the subject close to another light source to get their eyes to get used to more light and you have a better chance. Also try bumping up the ISO in low light, meter for the ambient light you have and use the flash to fill the shadows, you will get more pleasing balance pictures too, rather than the deer in the headlights look.

Err 99 usually means your lens contacts are dirty either on the lens itself or on the camera.

To isolate the cause of the issue, do the following: -
1. Turn off the camera.
2. Remove the lens, battery, and CF card.
3. Allow the camera to sit without power for approximately 20 minutes.
4. Insert only a fully charged battery, and turn on the camera.
5. Depress the shutter button as you would to take a picture.

Does the “ERR 99" message appear? If so, the camera may be faulty and requires a service. If it does not, then: -
1. Turn off the camera.
2. Insert the CF card.
3. Turn on the camera.
4. Format the CF card in the camera.
5. Depress the shutter button as you would to take a picture.

Does the “ERR 99" message appear? If so, then the CF card is faulty. Try a different card. If the message does not appear: -
1. Turn off the camera.
2. Clean the gold contacts on the lens by GENTLY rubbing them with a pencil eraser or soft cloth. Keeping the camera face pointing down, also clean the gold contacts on the camera, being careful that you do not let any debris fall into the camera body.
3. Reattach your lens.
4. Turn on the camera.
5. Depress the shutter button as you would to take a picture.

If the “ERR 99" message only appears when one particular lens is attached, then that lens should be examined by a service technician.
If you see the “ERR 99" with a different Canon lens attached, then the camera is faulty and should be serviced.

There is a small round pushbutton on the top of the camera marked with a clock icon. Pressing this button engages self-timer mode. When the camera is in this mode pressing the shutter release starts a 10 second countdown. The camera will beep during the countdown if the beeper is enabled and the top-deck LCD displays the number of seconds left. Two seconds before the shot the camera will beep faster and the red-eye reduction lamp on the front of the camera will flash to warn you that the photo is about to be taken. You can cancel the timer at any point by switching the camera to another mode (or turning it off) before the picture is shot.

Refer to the manual if you have it. or Canon customer support if you do not