Fine until I switched off router - now says I'm connected by cannot get on net

[#1]

Been with Plusnet for about 1 month.  Had tech issues originally but they seemed to be resolved.
Today I switched off the router   at the socket and now I can't connect to the internet wirelessly.  
Have been using Belkin dongles on 3 upstairs computers and now they won't connect.  
It now says acuiring network connection.
Daughters netbook works (using Windows 7 with built in wireless adaptor)
Computer icon says connected but cannot get on the net.  
I've changed the IP addresses manually but still no joy.
Any help please?  

[#2]

Poll removed as I assume it was an error

[#3]

Getting the message "acquiring network connection" suggests to me that the upstairs computers are not connected to the router. However you say the computer icon says "connected".
Those two statements appear to conflict to me?
Are you using the Belkin wireless connection manager? If so do the computers connect if you use Windows Zero Configuration (if XP) or WLAN AutoConfig (I think it is, for Vista) instead?

[#4]

Quote from: Longton433

Today I switched off the router   at the socket and now I can't connect to the internet wirelessly.

And switched it on again? You do know you need the router on to maintain the wireless connection, don't you?
Some routers allow you to change a parameter but don't save the change unless explicitly told to do so.  I don't know if that is true of the routers Plusnet supply or whether you are actually using one of those but this is a mechanism by which restarting a router could break a wireless connection.

Quote from: Longton433

I've changed the IP addresses manually but still no joy.

That was wrong and will make matters worse.  Please undo any changes you made.