Sometimes your needle may go through the strand of yarn instead of neatly through the loop of a stitch. These stitches are less stable and also don't lay flat. To fix these, you can rip back to the split stitch, undo it, and re-knit it correctly with the rest of your stitches. More easily (and if it is more than a row down in your work) you may prefer to unravel, or "drop" the specific stitch and fix it.
To do this, follow the column of stitches above the split stitch to the row you are working on. Drop that stitch off the right needle, and unravel it down to the split stitch.
Unravel the split stitch and then use a crochet hook to re-weave the stitches, as shown in the next section of this tutorial.
Picking up the dropped stitch
You can rip out your work, pick up the dropped stitch with the other stitches, and re-knit, or you can fix the one dropped stitch with a crochet hook.
On the knit side of the work, insert the crochet hook into the dropped stitch from below, front to back.
Grab the lowest strand of loose yarn above the stitch ...
... and pull it through the dropped stitch. This new loop is the new stitch.
Repeat until you have hooked the last strand, and place the rescued stitch back onto the knitting needles.