My network has stopped working.

[Flyiñg Ñuñ 2°16 + on desktop]

I have a simple network at home. My router is Technicolor TG582n
supplied by Plusnet, and connected to it by wifi are a desktop pc (Nova)
(Windows XP Home service pack 3), a netbook (Nettie) (Windows XP Home
service pack 3), a Sonyericsson Xperia smartphone (Android), a Median
Lifetab tablet (Android). The router is also connected to a Sky Plus
set top box by an ethernet lead.
Up to last Monday (14/11/2016) all was working fine but on Monday I
found that when I opened Network places Nettie couldn't see Nova and
Nova couldn't see Nettie. Strangely if I used tracert and ping from
Nettie to Nova then ping packets were 100% lost and tracert timed out
for all 30 hops, however from Nova to Nettie, ping gave o% packet loss
but timings were 329 ms, 2 ms, 2 ms, 2 ms and tracert gave 3ms on a
single hop. This repeats exactly in both cases with and without my
Avast shields enabled and disabled on both Nettie and Nova. I've
checked all the permissions I've given on both computers and all seems
as it should as far as I can see. When I try to use the Network wizard
on either computer I get the error message:
'Some of this computer's network hardware is still disconnected.
Before you can continue, you must either plug in or otherwise connect
all of your hardware, or select "Ignore disconnected network hardware."
The Wizard does tell me what the disconnected hardware is - and in both
computers it's the Ethernet adapter. Both computers should be connected
by wifi, and so, I thought aren't needed anyway, but I feel very
apprehensive about ticking the 'Ignore' tick box as I don't want do dig
an even bigger hole. I've checked the router Home Network page and both
Nettie and Nova, plus my wifi printer are connected and both computers
will connect with he printer, just not with each other.
I suppose my questions are:
(a) Do I just go ahead using the wizards by ticking the 'Ignore' tick
boxes, or
(b) should I start looking elsewhere first
Any ideas would gratefully appreciate any ideas as to solve the
problem. I cannot understand what could have happened to stop the
network working so suddenly after several years of it working
successfully.
--
Heard melodies are sweet but those Unheard are sweeter
flyi...@tiscali.co.uk FN 2º16+. Mungo Brandybuck of Buckland