No Sound Very suddenly (overnight) our Philips 37 Inch HDTV has no sound. The mute is not on and nothing was changed during the last viewing. The picture is great, just no sound. Please help...

Re the sound, make sure that the mute switch is not on.

Re the input, did you try changing input at BOTH the tv and remote controls. Could be the remote source button is not working.

Check its speaker first. If found OK, check and replace damaged component/s at its audio output card, or, replace it as card basis. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy.
http://electronicshelponline.blogspot.com/

LCD inverter backlight board is out 42pfl7432d/37

Mine did that and I went and punched menu and reset the TV back to factory settings and it's ok now.

replaced main board

The problem was caused by a loose conexion. One of the cables that goes from the DirecTV box to the TV was loose. The problem was FIXED by pushing the cables to make sure there was a good conexion.

Press menu and use the up or down arrows to find the audio section adjustments. Press the right arrow and again use the up and down arrows to find tv speakers, Press the right arrow to either turn on tv speaker or turn them off ( This is used only if you are using the output signal from you tv in to you stereo input to have surround sound.) Turn them on to listen to sound from the television speakers only. If this does not solve your problem, Press the mute button on you remote control to release the mute function. If all this does not work the telephone number for Insignia is 1-877-467-4289. Talk to them about you problem and see if your television needs some type of service to restore the sound. Hope This helps you with your problem.

Unplug for one hour then plug back in---worked for me--computer resets

I think it the main logic board!! I have 42 plasma samsung doing the same! change that works!! cost $124~~

Please elobrate further your problem.. i'm a bit confuse " If I press mute button it goes to mute,press mute again sound will come back on" This is normal.i.e. that is the function of mute button.