First let me explain my sinuation..

Ok I got as far as the first meeting with Sarovok, but then Belt died. So the last save I had was way back where you are underneath Candel Keep.

So I started back from there. But I forgot how you re-enter Candel Keep. You have to have a book, I think someone gives one to you, but no one did. How do I get in?

If you were under Candlekeep, then you've already done everything inside. You don't need to go back in.

First off, what about your Auto-Save?

Next, as Billy Yank said, if you're underneath Candlekeep you need to worry about getting out, not in. Check your Journal: If it's Chapter Seven, it's time to head back to BG city.

If, on the other hand, your last save is before you enter Candlekeep, you need to have the Book of Ancient Knowledge (History of the Nether Scrolls). Give the Book to the Keeper of the Portal and he'll teleport you inside.

Oh thats right!! Silly Silly me,