Reset hp pavilion screw up

I reset my HP pavilion entertainment pc and didn't do a system image back up . Now it asking me to add drivers and to insert the installation media for the device . I don't have it . Is there something I can do to help get my computer up and going again. I don't need any of the old info but would like to be able to play with it .and add some new stuff .I did it because I'm pretty sure there was a virus .so I tried getting rid of It .well I think it's gone but so is every thing else .please help. I do have access to other computers and I pads and tablets . So can I down load something and install it that way . I'm not overly computer savy nor am I an idiot so give me the run down on the directions and ill follow them . Help!!!!!!