I have MacBook Pro mc700 with OS X Yosemite installed.
A couple of weeks ago, I decided to format my HDD and install a fresh version of Yosemite, so I copied all contents of my iTunes folder into an external hard disk and installed the OS X. Now when I copy the iTunes folder back into my MacBook my iTunes app can't recognize it and so nothing happens. I know probably I've done something wrong about "just copying" the iTunes folder but I would really appreciate it if anyone could help me to save my old iTunes library.
I've run into this problem before. I believe it has to do with the library file that's created on your Mac when iTunes is ran for the first time. How I usually get over it is to do "File>Add to Library" and then pointing it to the folder with my iTunes media in it. This allows iTunes to create a new library file unique to the machine.