The crash may mean that they can't be resumed, but they should.

Repeat search, and if new sources for that file are found, once they start downloading the percentage should jump to the real amount.

If not, then the crash meant that the downloads.dat and .bak files in the Incomplete folder (they keep track of the incomplete pieces) became corrupted, and there's nothing else you can do.

I Hope they resume. . . that's a real pain when they don't.