Lens will not function

Sounds like the aperture control actuator ring in the camera body is not opening the aperture diaphragm blades fully a repair quote and decide if a different body upgrade may be a better option

problem in lens unit repair or replace

Lens error is usually caused by mechanical faults concerning lens assembly. The lens cannot extend or retract fully, the error is detected and lens error is returned.
Sometimes this can be fixed playing with the lens during extraction or retraction to help the lens asset getting back to normal.
More often the camera lens must be disassembled and re-assembled by a technician to fix the problem.

work for about 50% of lens errors, but they're worth a try. The list includes:

1. Remove the batteries and wait a few minutes
2. Try pressing and holding the Menu, Function, Function Set, or OK while turning on the camera, or otherwise find a "factory reset" option.
3. Try turning the camera on without a memory card inserted
4. Place the camera flat on its back and turn it on while holding down the autofocus button, to try to cause the camera to attempt autofocus while the lens is extending
5. Blow compressed air in any gaps around the lens - or use a shop vac
6. Use a thin piece of paper or a needle to dislodge any visible bits of grit
7. Gently tap the camera in an attempt to realign jammed mechanics or dislodge particles (obvious warning: could cause further damage)
8. Gently push or pull the lens barrel, as a last resort (again, potential for further damage).

The problem was caused by fine particles getting trapped between the sections of the lens. I tore off a thin strip of paper and wrapped it around the inner barrel of the lens. By rotating the paper, I dislodged the particles, switched on and the camera functioned normally.

Was this stuck fully open or was the lens partially opened, or was the lens jammed?

The lens can be removed and replaced with another lens from another non-functioning camera (See ebay). The lens component can also be dissembled. Putting the lens back together is tricky because the parts have to be aligned just right for the lens to work. If working with a Jammed lens, extra care has to be considered not to break any of the moving plastic parts of the lens or that part (if not entire lens) is junk.

With the motor detached from the lens, the lens should extend and retract freely. Use this to test the lens when you dissemble the camera. Be careful of the flash board.

The lens on my canon camera power shot A430 wont open and when I try to start it is says lens error restart the camera

You may have the same problem that i had. It does involve taking the camera apart. Not overly difficult - just fiddly.
Let me know and i'll talk you thro' it

The easiest way to take pics with the SE K810i, I just slide the lens cover and it auotmatically goes to camera mode

The switch that looks if the lens cover is opened is broken, you will have to ask a repaircenter to replace the switch for you, as the camera won't function without it. the switch is soldered on to a flex cable, thats quite difficult to solder by yourself.