I just installed limewire and when I put in a file to be searched the search button is not highlighted or dark. I click it and nothing happens. Why is this?

The only time the search button changes colour is immediately you press it and only for a very small moment.

Are you getting any search results?

If not, check that you are connected, the button in the bottom left hand corner should be green.

if it's red, go to File>Connect.

Sometimes you can get diconnected without realising.

Hope this helps a little

__________________
~Kath~
Always judge a person by the way they treat someone who can be of no possible use to them

In LimeWire 2.0 and above, the search button is disabled until you are connected to the network (since running a search would do nothing anyway).

So, as Kath alluded to, the problem is that you are not connected to the network. As she also said, try going to File>>Connect to get connected.