What should I do My Canon Powershot A540 digital camera doesnt work....?

when i turn it on it says Lens Error. Restart Camera HELP!! WHAT SHALL I DO

Sounds like an E18 error.
If it's still under warranty send it to Canon for repairs.

If not under warranty, I would shop around for a new camera.
The price you will have to pay to replace it, you can get
a brand new camera...

You might want to toggle the camera on and off and you might
get lucky and it will unjam..

Good Luck!