Try the advice in the thread below. Start off by deleting LW's preferences folder & updat1ng/changing your Java version.
all of a sudden will not connect (a fix to try)

In case you have Vista, things are a bit different to XP when finding the preferences folder & other files/folders within Application Data. This thread should help with that: LimeWire Pref Folder in Vista

if nothing there helps, please give us your details.
System details - help us to help you -> Provide these details when you post!!!