When you miss a promise, the person affected usually needs usable information before they need a speech about your intentions. Acknowledge the missed agreement and its practical effect.
State what happened accurately, including what remains uncertain. Avoid a confident replacement deadline until you have checked the work and its dependencies. A second unsupported promise creates another problem for the person trying to plan around you.
Offer a credible repair
In a fictional project, a guide promised on Wednesday is incomplete. Explain which part is ready, what remains and when the remaining input can be confirmed. Offer an interim version only if it genuinely serves the recipient's needs.
Ask whether their circumstances have changed. They may now prefer a reduced scope, another supplier or cancellation. Repair includes respecting that choice rather than insisting they accept your preferred recovery plan.
Change the cause
After addressing the immediate effect, review how the promise became unreliable. Was the scope unclear, capacity unavailable or a dependency hidden? Make one concrete change before accepting the next similar commitment.
Trust cannot be restored by declaring yourself trustworthy. It develops through subsequent agreements that hold. Keep the repair proportionate, specific and visible enough that the other person can decide what confidence to place in the next promise.