Easy and effective way of cleaning a point and shoot sensor?

I bought a Canon Ixus 105 last month and yesterday I found out that there were dark spots on the image of the blue sky, especially on the ones shot with narrow apertures and longer focal lengths. A dirty image sensor is not covered by the warranty as it was written and falls under the category of misuse.(the use of camera in dusty areas is not recommended). I opened up my cam and cleaned the sensor with a soft cotton bud and closed the camera again and checked for dark spots on image. But nothing happened. It was still there... Then I was putting the aluminium body covers back and they was very hard to put back, I think that they might have got bent while opening(aluminium body sucks)... So I was kind of hammering the cover back on it. And when I checked it again the dust moved to the top side of the cam. So, how do I get rid of it? And is the dust on my sensor or is it on the inner lens? And, can we clean the inner lens?(The lens was very complex, hidden behind layers of circuit boards, steel frame, shutter and lots of screws, and I was very scared to open it as the inner lens is very small and maybe almost impossible to clean)