Why can't I reconcile an account?

drfleming said:

I have selected my checking account and then the reconcile button, but it doesn't show any transactions later than almost three months ago. And, all of a sudden my account does not show any previous reconciles in its history.

First, I'd make sure that this is your current Quicken data file which is open, and not an older copy somehow. Do you see a steady list of your transactions from the current time back over the past 3-4 months? 

In your register screen, you're saying you see transactions from the past/last month, right? And when you click Reconcile, you select Use Statement Balance, and enter an ending date within the past month, none of those transactions show up in the reconcile window. Do you have the Clr column visible? (If not, click Columns and make it visible.) And the transactions from last month do not have a green check mark in the Clr column?