Only for understanding. You was working before with Calibre too? If yes, you need to move the
complete Calibre library folder with
all files to the new pc. Then make shure that Calibre knows at setup the library location at your disk. Donīt merge anything, only copy and let calibre know the location. If you do it that way it will work perfect.
Hope you have a complete backup of your old DB.
By the way, please choose the right place for a new thread. This one is the location for recipes