Yesterdays, I can relate! My room particularly is a huge giant mess and it overwhelms me SO much! I know I need to tidy it and I WANT to tidy it but then I look at it and think "argh!".
The rest of my house is fairly messy, too. We've been that way for a long time, since I was young.
I'm not sure of a solution, I mean, cleaning it is obviously the solution but when there's that much stuff it seems impossible, it's so overwhelming. But I don't know how to get the motivation, that's what you really need. I do know, however, that you and your family will feel so much better once it's tidied up a bit.
Maybe the key to keeping it tidy is to add more storage? More shelves, cupboards etc if it's possible??

Can you perhaps convince your family to have home cooked food more often? Maybe even offer to cook it yourself. They will save soo much money and be so much healthier! Or maybe if they still want take out you could buy your own food and eat separately?

Good luck, I hope you sort things out x