Do you mean you're having trouble downloading LW itself, or downloading files using LW? LW can be downloaded at the official site here...that's the only place to get an official, clean version
LimeWire: The Official Site for the Fastest File Sharing Program on the Planet

If you're having trouble downloading files, check out these threads for advice & tips.
Fake files showing up in search results
How to find music (has tips for video also)

Check the stickies (in red) through the different forum sections & have a read through the Userguide & FAQ as well