My cards are blank?

I’ve made around 400 cards for school this year, I add a front and a back on basic cards but recently I clicked on a card and it said ‘this card is blank’, it’s doing it for all of the cards now, what do I do?

As I say, I added a front and a back so I’m confused why it won’t let me practise them.

an idea:

In Anki you create NOTES. According to rules you set in the card templates window Anki automatically generates CARDS from your notes. You review these CARDS.

In the card templates window you can set stuff like “As the question show the contents of the field FRONT”. If by accident you have deleted this all the CARDS your review would be empty. Does your Front Template contain something like {{Front}} (or however the first field of your basic note type is called in the language you use).

Distinguishing between notes and cards might seem complicated at first but it’s a really powerful mechanism that can save you a lot of time in the long run.

for details see