Totally clean installation of LPE.
You will have a preferences folder now at least. But you need to turn on Show Hidden Files & Folders before you can search for it. Either with search or manually finding it.
LimeWire and Java Reinstallation Technique l
Another option to try is to download & install
FrostWire & see if it runs & connects ok. If yes, then close it, open LW.
One problem with LW 5 is, if it has not been used for a certain period of time, it is programmed to delete the connection file itself. I think File_Girl produced a fix for that. I think that was a separate program utility installer fix.
Edit: Oops my first link didn't work. Fixed. Sorry about that.