I lost a card from my deck. Should I kee

Yes — keep reading with it. A 77-card deck reads perfectly well; nothing in the method depends on having all 78.

What actually changes:

• Uniform draws still work. The one missing card simply never comes up; no seat is left unfilled, and the spread doesn't develop a hole where it would have been.
• Don't substitute mid-reading. If a position feels empty, draw the next card and read it as what it is. Inventing the "missing" card is how a reading quietly turns into something you wanted rather than something that happened.
• Write the card's name on the box or the inner flap. That's it. Most finds happen when you're not looking — under a sofa cushion, a coat pocket from the winter. If it turns up before the deck is ever needed again, you're back to a full set.
• If it's never found, buying a second deck is not cheating; you just use whichever deck you hold, and you note in your journal which set you're reading with so a pattern isn't silently split across two physical decks.
• One rare case to avoid: if the missing card is a Major Arcana card, some readers like to treat the deck as temporarily closed for major questions. That's a tradition, not a rule — and it only holds if it means something to you.

Practically: the deck you have is the deck. Start your next reading whenever you like.

If you'd like, I can pull one card as a "lens" on where to look for it — a small pointer, not a prediction; or I can save this as a note in your tarot journal so the missing card is on record.