How do l find an error when mu quickbooks wont reconcile?

Hello Elaine, Thanks for reaching out to the Community! Do you have a resolve difference error? If you click on the writing it should tell you what has changed in previous reconciles to cause the difference. Generally, it would mean previously reconciled items were edited or deleted to cause a change in the balance. Are the deletions/edits correct or have the transactions been re-entered after deletion? If however, you are referring to a current reconciliation in progress that is not balancing let us know and we can provide some pointers on why that might be.