User friendly non specialist setup guide

[the_bertrum]

I am CERTAIN that this could be explain in a much clear and simpler way if someone wanted to and was sensitive to non advanced users

To some degree you are right, this can, and even is, made easier all the time.  There are a myriad of "plug and play" network music streamers to be had that come with abundant instructions and are designed specifically for ease of use my the non technically minded.  Of course all that user friendliness comes at a cost. One price you pay is in the form of more money to buy in, you need hundreds of pounds instead of tens. Another price is lack of customisation, you can't add bits to make them work like you want, you can't rewrite the code to remove an annoying obstacle, you can't choose to build your own interface that suits your own desires and needs.
You have chosen to buy a computer designed for hobbyists and those wanting to learn fundamental computing principles, attached a device designed by audio nerds who enjoy tinkering, and then put software on it that is developed by a group of talented enthusiasts, it will need some work on your part.

Having said that, you also have access to the combined wisdom of those talented enthusiasts through this forum and if you are willing to learn, it can be rewarding.

I see that you have have got as far as getting the UI up on a PC when the Pi is connected to your router via an Ethernet cable, that is probably the best set up to begin with for someone starting where you are.
You will always be able to get to http://moode.local if there is a working moOde installation on you local network (local network is anything attached, by cable or wifi, to your router, it can be more than that but these purposes that definition will do).  The fact that you did get the interface and now do not suggests that the network is OK, but that something is amiss with your device.  The first thing to check is that it did actually restart and not just shut down.  To do that simply turn off the power to your Pi (just pull the plug out, it won't hurt anything).  Then make sure that you have your ethernet cable connected to your Pi and the router, and that your PC is connected to the router too (by cable or wifi).  Then plug the Pi back into the power, you will see the activity lights on the Pi flashing quite a bit, and the lights on both ends of the Ethernet connection should flash also.  Once they all calm down a bit, try the moode.local address from you PC again.  Chances are you will see the UI again and can continue to configure things.  If you don't see the UI try again in a minute or two, and remember to try a "refresh" in the browser just in case (press "F5" is the best way).

Let me know how that goes and I'll see if I can help you with the next steps.