Hmmm not sure have you gone to the LimeWire library and highlighted the incomplete folder. This will show you the incomplete files. Highlight one of the files then click on the resume. This should move it back to the d/l window.

It would be best to do a manual search in the search window to see if you can locate the file to see if any hosts have it available for d/l, before you tried the resume option I mentioned above. Better to have sources/hosts available when you resume this way it should automaticaly start to d/l from where it left off.