Moved i tunes from old laptop to new and cant play older music

I saved my old library to a cd and transferred it to my new laptop. Now I can only play anything new that I purchase and/or add although all my older songs appear in my library.

The message I get when I try to play them from my laptop is along the lines of ' i tunes cannot locate file'.

Does anyone know how I can solve this before I give up and sign up to Spotify!

Thanks in advance.