My hp all in one 6500 keps saying that i cant print because its not connected to a computor but it is?

If you're getting an error about the connection you have to make sure that the USB cable (if connected by USB) is plugged in correctly, or you may try reseating it.Unplug the USB cable. Reconnect the USB cable to the back of the printer and plug the other end to a USB slot in the computer. Make sure that you hear a sound in the pc when you connect the USB, that means that your pc has detected something. Also try downloading a Print Diagnostic Utility from HP website, this tool is pretty useful printing probems.HP website, then click on Support and Drivers, then go to Download software and drivers, key in the product name and hit enter. Choose your OS and hit next, click on Utility and Diagnostic Tools and click on HP Print Diagnostic Utility.
If connected wirelessly, you can also try the HP Print Diagnostic Utility. If you get an error on connectivity, make sure that the printer and the computer are on the same IP address. If both have the same IP address and your pc still can't detect the printer try updating the software by downloading it from HP website.