I’ve been out of my house for 3 months. Smart tv works - SKy + box not working. Source +wifi all ok

[Darcoo]

I've not been home for 3 months. Switched tv on today all ok. Sky will not connect. Power is ok. I've switched it off for ten minutes. Same with the Wi-Fi which is working fine. The tv says to check the source. All ok. I've checked cables etc. all seems to be in order - just won't appear on the screen. Just a blue screen. Smart tv working fine. 
I have a Sky + box

any ideas!? 

[Mark39]

Was your Sky box plugged in and switched on while you were away? Is your TV switched to the correct input source - that is, whichever HDMI socket your Sky box is connected to?

If all seems to be ok, try putting both your TV and your Sky box in standby then removing the HDMI cable, Swap the ends over and reconnect, then switch both back on and ty again.

[Darcoo]

Hi. Tv and box all plugged in and on standby the whole time. 
I'll try unplugging everything and starting again.....