In this forum you're not talking to Apple, but to users just like you. If you want our help, you need to post details. What version is your OS? Have you applied the latest printer driver updates from Apple? The software you downloaded was from Apple or from HP? What steps did you follow to set up your printer? What happens when you try to print, do you get any error message? Is it the same in all applications?
Is your issue fixed now? If not, you may come back with some more details as already mentioned by others.
You may also check out on the HP forum. I found this thread that might be helpful?! http://h30434.www3.hp.com/t5/Printer-All-in-One-Install-Setup/HP-Photosmart-7515 -on-PC-v-Mac/td-p/1123115