I've tried reconnecting all the wires.

Most combos I see have one set of inputs and outputs. You actually have to switch between DVD and VCR mode on the combo unit itself. The TV sees it a DEVICE... not as a DVD and/or a VCR separately.

I've switched it on the unit itself and with the remote, it just will not recognize it??

You need to elaborate on "not recognize it". If one part works and the other doesn't. Then you have a defective combination unit.

The TV doesn't recognize what they are. Just that something is there. If one part works... the TV and its interface with the unit works. If you mean the TV remote control doesn't recognize it, you will have to deal with several remotes.

The VCR is working, but the TV does not see it.

How do you know its working then... if there is nothing coming out of the video output when the VCR is switched on... but it does when the DVD is switched on... then its not working.

The TV doesn't CARE if its from the DVD or the VCR. Its from the same cable... if nothing comes out when the VCR is turned on... but it does when the DVD is turned on... that combo unit is bad. And a combo unit has to be both turned on... then the source selected between the DVD OR the VCR. Unless you are operating that unit incorrectly somehow, then its defective.

Incidentally... I have an engineering degree in electronics, and got it 30 years ago.

OK Thanks for your help!