Don’t worry or panic. In Jain Dharma, bhav (intention) is more important than just the body’s action.

Since you already ate something tonight by mistake:

1. Be honest with yourself

- Accept calmly: “Yes, I have eaten, so today cannot be counted as a full upvas from previous sunset.” - Do alpa‑prashchit (small repentance): Silently say Navkar Mantra and “Michchhami Dukkadam” with true regret.

1. Decide clearly for tomorrow

- Tomorrow morning (before eating anything), take proper pachchakkhan for upvas: - “Today I will do upvas as per Jain maryada. I will not eat any food for the whole day, I will take only allowed boiled water (if your tradition allows), only in daytime.” - Then keep the fast carefully the whole day.

1. What you should NOT do

- Don’t keep thinking “My upvas is spoiled, now nothing has value.” This negative feeling is wrong; it reduces punya. - Don’t lie to others. If someone asks, you can say simply: “Kal raat galti se kha liya tha, aaj subah se me upvas kar raha/rahi hoon.”

1. If your sangh has a rule

- Some follow strict rule “upvas = sunrise to sunrise.” In that case, count tomorrow as your proper upvas, starting from tomorrow sunrise to next sunrise. - If health is weak, you can instead do ekasan / ayambil with right pachchakkhan.

1. Inner attitude

- Focus on ahimsa, samyam, prarthana, pratikraman tomorrow. - Bhagwan sees your sincere effort and repentance, not small technical mistakes.

If you want a simple upvas-pachchakkhan to say, you can read more here