Sorry to hear that the installation cannot load now. Are you getting any error messages? I am curious if you received a fatal error or just "unable to find printer" error message.
I am quite familiar with your model of router. Your TG862G router had a recall on it a year ago or so and now their web page no longer references it. You may need a firmware update on the router and I may refer you to contact Comcast to help you with that and to identify if this model of router is still out-of-date. That is if a connection cannot be established soon.
Before attempting to re-install, go into the Network menu on your printer and print a Network Configuration Page. If it is not connected or there appears to be some wrong information, restore network defaults and then re-install the software.
If the printer has an IP address, then it is connected already. The wireless radio can also be turned off and that could cause the printer not to be found as well.
Did you try to reinstall from the software disc or the download at www.hp.com/support? Let me know why you can't load the software or at least a little more information as to what happened now so that I can assist you with that. I'm always happy to help.