A lot of people seem to be recommending the Feynmann lectures, but I'd recommend that you use those to supplement other reading rather than as your main text.
If you want to get up to speed quickly, try University Physics by Young and Freedman. It's a well written general physics textbook, contains plenty of exercises and diagrams (important!) and should get you up to a basic 2nd-year (UK) physics undergrad level.
After that, look towards the Manchester physics series. Electromagnetism (Grant and Phillips), Statistical Physics (Mandl) and Optics (Smith and Thomson) are all pretty good, and cover the bulk of classical physics. (University Physics covers dynamics well enough by itself.)
For quantum mechanics, I found the early chapters of Molecular Quantum Mechanics (Atkins) instructive. There are a few good relativity textbooks out there, but I can't remember the names of any...
For astrophysics textbooks, Introductory Astronomy and Astrophysics (Zeilik and Gregory) covers the basics. For high energy astrophysics, Longair is the most comprehensive textbook I've found. For galactic astrophysics I read Combes et al., which I found quite average.