>>>i have been told sometimes when sky is installed the aerial wire is cut
I can't think of any reason why that would be necessary but . . .
>>>one of the wires which look like an aerial wire has been cut, would it be as simple as just re connecting this wire ?
It wouldn't do any to try it. Use the proper connectors though, to ensure that good screening of the cable is maintained:
http://www.ebay.co.uk/itm/like/330908697450?hlpht=true&ops=true&viphx=1&lpid=95&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=95
(They're widely sold in discount stores, etc).
However the first step might be to see if you can actually locate an aerial. Reconnecting the cable won't help if there's no aerial on the end of it!