Lens error the lens is constantly out and when i switch on the camera i hear a rough noise and lens error come on the screen

You don't need to drop a camera to get a lens error. Could be anything, from holding the camera in a wrong way (touching the lens barrel) or a bit of dust in the barrel or a gear, or a gear that breaks off. If the lens retracts correct when the camera is switched of, and comes out to the full extend when it is switched on, you should think everything is in working order. But when you say, the screen looks ver blurry that could be an indication, the lens is not coming out correct, or the focus mechanics does not work correct. I'm afraid you have to bring the camera in to a service centre (or buy a new one) if you can't solve this, by again take out the battery, charge the battery and reinsert the battery.

Low Battery, or exhausted ones, also gaves error 00, due to inability to provide high power to the lens.

Sounds like the focus motor came loose - you need to take it apart and repair the gear that drives the lens assembly for focusing. The noise you're hearing is the motor trying to focus but since the lens cannot focus it continues to run and signals an error.

This is probably THE most common failure among digital cameras. There's a halfway chance of fixing it yourself, described here: http://camerarepair.blogspot.com/2007/12/fixing-lens-error-on-digital-camera.html

Use your thumbs and gently yet firmly push the lens assembly back into the camera until you hear a confirmation "click"

I just gave it a very hard tap against my dinning table and it became alright!

The following blog outlines some repair options for a lens error:

http://camerarepair.blogspot.com/2007/12/fixing-lens-error-on-digital-camera.html

The lens mechanism is shot. An economic repairs is not likely. Contact Canon Customer support however.

E18 is the error that comes when when the lens is stuck, so if the lens is stuck out, turn off the camera, carefully turn the lens until you hear a small clicking noise, then turn it on. I had the exact same problem, and that fixed it for me

hi the problem that causing this is: there is some pressure to the lens did it fell? probebly there is a fault in the lens sorry cant help good luck