'Error 99' indicates some problem with the AF contacts. This is a common error in Canon lenses. It could indicate a very simple problem like dirty contacts or a much serious one like the breakage of USM cable. Alternately, it can also be a card error or camera error.

First remove the lens, battery and card and leave the camera like that for about 30 min. After that, insert a fully charged battery and switch on the camera. If the error still shows up, it is a fault with the camera and has to be serviced.
If not, turn the camera off and insert the card. Format the card in the camera and depress the shutter button. If it shows an error, the card is faulty.

If not, try cleaning the lens and body contacts (the metal contacts between the lens and body) using a pencil eraser. Be careful to hold the body facing down so that no dust falls inside. After cleaning both the lens and the body contacts, re-attach the lens and try shooting.

If the error still shows up, you need to take the lens to an authorized service center.

Hello

The problem is that the lens has become stuck in the barrel. There are some DIY solutions you could try, but the probability is that you will have to get it fixed by a professional.

Use these at own risk as it may further damage the camera.

Firstly , try connecting your ac adapter or usb cable.

Try holding the shutter button while switching on the camera.

Look at the lens , and if some of the lens 'circles' is misaligned or not concentric then try wiggling it (while holding camera lens down).

Try gently pushing or pulling the lens when it extends but this is risky as it may cause the lens barrel to slip out of its guidance system.

Another way to do this is to place the camera lens down on a hard surface and then power it up. Be sure to use a soft cloth or something similar as to not scratch your lens or casing. Let the lens push the camera up and down a few times and sometimes the little resistance provided by the camera is enough to get things going again.

Try hitting your camera near the lens on the body with the soft tissue on the palm of your hand.

Other than that , I would take the camera to a repair center for a evaluation to see if it would cost more to repair than to replace the camera.

If it is still under warranty I would suggest you take it in before trying any of these steps and remove any off-brand batteries or accessories as some stores are really fussy about warranty repairs on camera's with non-brand accessories.

Hope the advise is useful. please do not hesitate to let me know if you need any further assistance.

Regards
Andrea