Cheated...

Who knows...you didn't log it.

No seriously, do your best to go back over your memory and fill in the gap. It's a learning opportunity. Everybody has bad days and makes mistakes but there's no way to know what damage was done if you don't log it.

Your body will calculate it whether or not you do.

Unlikely you've lost all your progress.

If you're averaging loss of a pound a week, eating an extra 1000 calories is only about 2 days delay in reaching ultimate goal weight. Now, if you do that often, it starts to be a problem. Once a month or less? Not such a biggie.

Look: Over-goal days are going to happen occasionally. I'd argue that it's best to log them, even if you have to estimate.

That way, you can see an estimate of the calorie impact, translate it into the number of hours/days delay in reaching ultimate goal, and decide whether it was worth it (IME, sometimes it is, sometimes it isn't - knowing this helps shape future behavior).

Also, you can look back over a longer time period in your diary, and think about what influences you to overeat: Not enough calories the previous day, or not enough of some macronutrient (fat, protein, carbs, fiber)? Light/no breakfast but you need more? Heavy breakfast you could've skipped? Protein-heavy vs. carb-heavy breakfast (or some other variation)? More or less exercise than usual that day or the day before? Alcohol consumption involved? Didn't drink enough water? Social trigger? Food trigger? Etc.

You can even consider putting other things in your diary notes, like how much sleep you got, and what your stress level was, etc. These can affect appetite and discipline, too.

You can make weight loss all about sin, guilt and retribution (not to mention unnecessary drama). Or you can make it a fun, educational, analytic science-fair project. For me, the latter was a better way to lose 50+ pounds, to achieve a healthy weight, and to maintain that weight for a year-plus now. YMMV.

P.S. You may see a bigger scale jump for a couple of days or so from water weight due to the extra carbs and extra sodium in your over-goal eating, plus the extra digestive system contents. Don't worry, it's overwhelmingly not fat. It's temporary. Just get back on a healthy routine, and it'll drop off.