When i turn on my nikon camera the lens goes in and out a million times and makes a clicking noise and then says lens error.

SOURCE: Lens is stuck open and making a clicking noise!

It costs more to fix than replace. It's quite asinine. And I wouldn't recommend Nikon again.

SOURCE: Nikon S200 Lens stuck inside

I had the same issue with my S210, so after reading other people's advice to send it in to Nikon and since that was going to probably cost me as much as the camera itself I figured it wouldn't hurt to try a little something. The lens on mine was a hair off center or had been pushed in on one side (barely - looking at yours you may be able to tell which side) - mine was in my purse also. So, I took my handy dandy skinny prying instrument (normal kitchen butter knife) took the battery out to make it try to open again, then when I popped the battery in as the lens tried to push out I pried the side I thought was a little lower back towards center...I heard a little pop and it worked! The lens came all of the way out and it's all good.

So, use gentle hands and try if you want, but don't think I warranty this!

SOURCE: Blurry images (after a lens error)

There is a mechanical displacement in your camera. Definitely, it is not a software problem. Actually Digi Cams are very delicate, especially small ones.... So get it serviced from a authorised service station. They will fix the problem....
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SOURCE: my nikon s220 shows lens error and the lens remain

Clicking noises suggest the lens is either knock damaged or jamming because of sand - probably a marginal repair.

SOURCE: my digital camera has a lens error

Try one of these two fixes, if they dont work for you follow the link below for further troubleshooting.

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

Fix #1: Remove the batteries from the camera, wait a few minutes. Put a fresh set of batteries back in (preferably rechargeable NiMH 2500mah or better) and turn the camera on. If that didn't work, try pressing and holding the Function or OK button while turning the camera on.
Fix #2: If the camera's batteries ran down completely while the its lens was still open, the camera may show a lens error or not start properly when new batteries are installed. Remove the memory card and keep it removed, then install the new batteries. When you turn the camera on with the card removed it may come back to life, as this triggers a reset in some cameras. Error E30 (for older Canon's) means that you don't have a memory card installed, so turn it off, slip in the SD card and turn it on one last time