If the new pictures you take don't look right, then this sounds like a CCD imager failure. Canon has an on-going free repair program for this. See this link:
http://www.usa.canon.com/cusa/support/consumer/digital_cameras/powershot_a_series/powershot_a70?pageKeyCode=prdAdvDetail&docId=0901e0248013d2f6
However, if the new pictures you take look okay, then you've got another problem.