NMR spectroscopy can be a daunting topic but there are numerous excellent books with a variety of different levels of theoretical detail.
Spectroscopic Methods in Organic Chemistry
D H Williams, I Fleming
Covers the basics well and contains useful tables of data
Spectroscopic Methods in Organic Chemistry
M Hesse, H Meier, B Zeeh
Covers the basics well and contains useful tables of data.
Structure Determination of Organic Compounds: Tables of Spectral Data
E Pretsch, P Buehlmann, C Affolter
Contains extensive listings of spectroscopic data, but little by way of explanation.
Structure Elucidation by NMR in Organic Chemistry
E Breitmaier
Contains worked examples and covers most topics.
Introduction to NMR Spectroscopy
R J Abraham, J Fisher, P Loftus
Good coverage of the field including much of the theory.
High-Resolution NMR Techniques in Organic Chemistry
T D W Claridge
Excellent and painless introduction to NMR theory.
Modern NMR Spectroscopy - A guide for chemists
J K M Sanders, B K Hunter
This book and its companion volume provide a painless introduction to NMR theory.
Modern NMR Spectroscopy - A workbook of chemical problems
J K M Sanders, E C Constable, B K Hunter, C Pearce
This book and its companion volume provide a painless introduction to NMR theory.
Spin Dynamics: Basic Principles of NMR Spectroscopy
M H Levitt
Advanced NMR theory