The Canon PowerShot SD500 Elph is a 7.1 megapixel camera with a 3x optical zoom. The camera was released February 2005 and is identified by model number PC1114.
The battery may not be charged enough to turn on the camera. Take out and charge the battery for 5 or more minutes and then put the battery back into the camera.
The battery may also not work anymore or won't hold a charge, and in this case needs to be replaced.