Put the photos in the EXACT same location as they were in before the crash; put the pictures.LRCAT file whereever you want it to go and then double-click on it.
Thats part of the problem I don't know the EXACT locations of the files, it was a grab and hope job, while the drive was still running. the photos I'm missing is there any way of using the previews to rebuild any of the photos to any extent
My original reply probably wasn't as clear as it should have been. The key requirement is that you have all folders and all photos in the exact same hierarchy as before the crash — in which case you don't have to put individual photos back into the same folders, you just have to move the entire folder hierarchy back to the original location.
Aren't the photos you have, or true backups, in the identical folder structure as the originals? Are the photo files the same name as the photos in Lightroom? (And I don't understand what "grab and hope job" means, but its probably irrelevant, we need true backups, not "grab and hope" files)
If not, then you are basically in a world of trouble.
If you had to wipe the hard drive, then you wouldn't normally have access to previews.
If the photos are in the same folder structure (and same file names) as the originals, then you shouldn't have any trouble moving the entire folder hierarchy back to the original location. If you open the Lightroom catalog, it will tell you the name of the folder locations, should be easy enough to find the location specified by Lightroom and then move the entire hierarchy of folders to that location.
Thanks for the reply i understand a lot better thanks. By grab and hope was, i realised the drive was crashing so i got a backup drive and just got hold of files and dragged them to the backup, hoping the contents were in a useable condition. I will try and use the lrcat files to reassemble the file structure the best i can. the previews.lrdata could that be used to get back pictures that are lost or corrupt.
I appreciate your time in helping me with this very much.
It sounds like you are not making regular automated backups of your catalog file and photos. If that's correct, then you are living very dangerously, and you will need to begin making regular automated backups. There are third party programs that can do this for you. You got lucky this time. Next time, its possible you won't be able to retrieve your files. A word to the wise ...
I just marked the answer as correct because i believe thats going to be my only solution. You are correct that i have not been making regular backups, i was a fool in thinking it would never happen to me. Fool that i am.
Again thank you for listening and helping me out of a difficult spot