OT: IT Techy person - help with accessing wireless network???

[Guest guest]

We have home network, when we try to add a new machine it says the computer did not asign you a network address and won't work.

I think the last PC man that came when we lost code (Dh used highliter pen to write on glossy paper and then close it so all washed away) I think he has done something to it so every time we want to add new PC we have o ask him in at £45 for 6 mins. Can anybody help me past this, I'm not a numpty, can work by instructions

TIA

Mandi x