Hello, I’m Nathan, and I’ll be assisting you today.
Sorry to hear that you’re having trouble with this but I’ll do my best to help you out.
My apologies for any difficulty you have had in getting an answer. Would you still like assistance with this?
If so, I'd be happy to help you either here or by phone if you prefer.
The issue here is that the cords you are trying to use are simply not compatible or supported. All bluray players made after 2011 did not have the red/white/yellow ports at all.
The only possible connection that can be accepted between your samsung BD-J5100 and your panasonic TH-42PX77U is a HDMI connection.
HDMI cables are inexpensive and readily available anywhere that sells any type of electronics (target, best buy, walmart, even home depot). You can also order online, or just see an example of one here: http://amzn.to/2bF8bP9
You would plug one end of the hdmi cable into the HDMI OUT port on the back of the samsung, the other to the AV IN 2 port (for example) on the back of the tv.
You'd then use the TV/VIDEO button on your panasonic remote, pressing it repeatedly to cycle through the menu options (or pressing once, then arrow down) to get to the AV IN 2 (hdmi2) input mode. At that point the signal from the samsung should come through, and you'd control the player functions from the samsung remote.
If you get stuck, or need more help at any time, just let me know.