Without some information it is very difficult to give any advice.

Since you were able to connect and cannot now - it seems likely that something has changed. What has changed on your system?

Perhaps if you provide a little information:

What Operating System?
What version of Java?
What version of LimeWire?
What type of connection?
Are you connecting to the internet *before* starting LimeWire?
Have you tried "telnet router4.limewire.com 6346"?
Do you have a router/firewall/network?
What do you see on the connection tab of LimeWire?
Have you read the FAQ?
Have you searched the forums for something that looks similar to your problem?
Is there any other information that might conceivably be of some relevance to your problem?

Mark