Library not recognised

Hi,
I've spent months downloading my metadata on about 1500 books. I just had a reinstall and the Calibre Library went back from my backup OK. I've downloaded Calibre and pointed it to the Library but it is not recognising all my books. The ones it does recognise are mostly minus the metadata. There are no series showing either.:(
Is there anyone can help me. This is very frustrating.
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