Originally Posted by itimpi
Simply putting the files into the Calibre folder structurewill not make Calibre see them. I suspect that you will have to add them all back in via the "Add Books" facility.
Just for interest how did you delete the old TXT format files - vai Calibre or directly using Operating System level facilities. You should always do this sort of thing via calibre if you want to keep Calibre in step with the underlying file system.
I tend to not delete old file formats as disk space is cheap and I may want to come back and convert again for some reason. Calibre does not mind keeping multiple formats of the same book around.
I deleted them from within Calibre, I highlighted all txt files then did the search and all the newly created mobi files had gone too.
The only reason I wanted to delete them is because when I sync the new Kindle I only want mobi files to be synced. Will Calibre send every file or only compatible ones? If it is the latter I won't bother deleting.