How to fix the first two greyed out columns on Numbers?

I have made a spreadsheet, and my little dog has jumped on my iPad and did something, and I can’t figure out how to undo it. It’s too late to press the undo button, I’ve edited it too much before realising.

The first two columns are now grey, and when I swipe to the right, the two columns stay in view but the rest of the data columns disappear. I’ve tried to take pictures to show what I mean.

TIA!

[Re-Titled by Moderator]

Original Title: Please help me undo what I have done!