My iMac stopped connectin to an HP8500 A910 printer. Can anyone help?

My iMac is running Mac OS X Lion 10.7.5. Two weeks ago, my HP8500 A910 wireless printer stopped working with iMac. To trouble shoot, I tried the following:

- checked that my HP printer has a wireless singal

- checked my network rounter to ensure the printer was connected to the router

- tried printing wirelessly with my MacBook Air that is running Mac OS X Lion 10.7.5 and am able to print with no issues. My HP laptop that is running Win7 works fine

- on my iMac, I went into 'System Preferences' - 'Print & Scan' - Clicked on the '-' to remove the HP 8500, then clicked on the '+' to add and within the 'Add Printer' window the HP 8500 does not appear. I tried rebooting my computer to see if that might reset the system and went through the previous steps but no HP available.

- then went back into 'Print & Scan', right clicked and then clicked on 'Reset Printing System', clicked OK, then clicked on the '+', went to 'Add Printer' window and still no HP

- then I tried 'Utilities'- 'Disk Utility' - clicked Macintosh HD, clicked on 'Verify Disk Permssions', that ran and when finished I clicked on 'Repair Disk Permissions', that ran and completed successfully - then I closed any windows that were open - rebooted by iMac and went back into System Preferences - Print & Scan, Clicked the '+' and still no HP in the 'Add Printer' window.

My HP printer works fine with my other apple & windows devices.

I have tried everything that I researched and now hopefully someone has another idea that may work.

Thank you.