Onkyo tx-sr707 receiver- Lost sound. Tried Reset.

SOURCE: how can I reset Onkyo receiver TX-SR602 without

press and hold vcr 1 button and then push power button, it will reset

Testimonial: "You are genius and excellent, thank you for your help!"

SOURCE: Onkyo tx-sr800 PROTECT mode

Hold video1 and press speakers A button, it will say "clear" If the message protect appears again, then its service time.

SOURCE: Onkyo TX-8522 stuck on standby

This is Not a real Fix, However it stops the problem!
Do not plug any power cords into the Receiver.  I have found that using the "switched or unswitched" plugs in the back cause the trouble. 

SOURCE: Onkyo TX-SR705 Muting Problem

if what Dark_Orbit said does not work try doing a master reset by ressing and holding the dvr/vcr button and stand by button simultaneously. This would erase all your assignments so you would need to reassign all your sources hooked up to your onkyo.

SOURCE: connecting a wii to an Onkyo TX-SR607 7.2

I am experiencing issues like this although with a VCR connected with analog video. I added a BluRay DVD player and all of a sudden I lost my video upconversion from my VCR. I am going to try to reset the receiver to see if this fixes the problem. If not, I don't think it is the receiver issue, I think it may be the fact that enorder for video to pass through HDMI, allot of criteria needs to be met. Certain Handshakes need to happen, especially with the HDCP issues. Most likely I will connect a separate video cable to my Plasma and use a secondary input on the Plasma for the VCR signal. You may want to purchase the Component Video adapter for the wii system as this will provide you with at least 480p and your receiver should not have an issue passing the signal over the HDMI output. Good luck and give me an update.