What's your connection like - do you have any green bars at all?
Do this test & see if it works
http://www3.limewire.com:6346

What are your details (sorry for any repeat questions!)

OS(Win XP etc)
LW & Java version (help > about LW & you'll see)
Firewall you're using
Modem/router brand & model
ISP
Connection type (DSL etc)
Where you connect from (home, school etc)
Are you sharing a connection with other computers
Is this your first try with LW

Have you tried using any other p2p apps & if so, do you have the same problems?