# Lost in the middle of an algorithm

Everyone does it: one wrong turn and the layers you'd finished are scrambled.

## If you know where you stopped

Undo the moves you've done, in reverse order and each one reversed (`R` becomes `R'`, `U'` becomes `U`). Then start the algorithm again.

> 3D demo, Undo: R U R' U R U2 R' is undone by R U2 R' U' R U' R': `R U R' U R U2 R' R U2 R' U' R U' R'`

## If you don't

- **First layer still intact?** Start again from the step you were on. Only the layers above it are affected.
- **Everything messed up?** Scan the cube with ScanMyCube and follow the solution move by move. It shows each turn on the 3D cube.

## Common mistakes

- **Guessing at a fix.** Random turns usually make it worse. Undo, restart the step, or scan.

Source: https://scanmycube.com/help/lost-mid-algorithm