How to use "failed to import" txt file to retrieve complete photo selection

There is no option provided in the import dialog to use a text file to select images. I think the error text file is purely informational. This might be your only record of having individually checked and unchecked a lot of images to include / omit for import, in which case the only way it could be practically useful AFAIK might be to programmatically find those images and separate them to a dedicated storage location - by writing a script or some such to carry this out (externally to LrC). Then import whatever's in that new location. Or you can refer to the text file to carry out the same separation manually. 

I don't fully understand what may have caused the import error - but if some images were successfully imported at an undesired location, while other images failed to come in, the successful imports could need attention also. These would not have been reported as errors.

If the entire import failed then you can simply repeat it with the desired settings.

Perhaps if you can be specific setting out what you wanted to happen - and what did happen - you can get some more specific advice back.