I am unable to get. I am unable to get my HP scanjet 4850 to work with Vista. and now I have

Question

I am unable to get my HP scanjet 4850 to work with Vista. and now I have uninstalled it to try again, I cannot now find my reg. no. It was purchased a couple years ago and registered in my name Maggie Salisbury - [e-mail]. I have now changed my email provider to optusnet. so it is [e-mail]. Is there any way of getting my reg. no again - first question and second question, how do I get my scanner to work with vista. I have downloaded all the drivers from your website and still no luck. I am using a Compaq zpresario SR5240AN Desktop PCThank you Maggie Salisbury