In stockinette stitch: To rescue a dropped stitch from the knit side of stockinette stitch (if the purl side is facing, turn it around), reach through the dropped stitch with a crochet hook and pick up the bottommost strand in the ladder. Then, pull the strand through the stitch toward you to form a new stitch.
To pick up a dropped stitch purlwise from the outside, you need to recreate the purl â€œbump.â€ Insert the crochet hook into the dropped stitch from back to front, and use the hook to pull the strand through the loop from front to back. When you pick up the dropped stitch, the fabric might appear loose or elongated.
Knit until you've reached the dropped stitch. Insert a crochet hook (if you don't have one available, the top of your needle will also work) into the loop of the dropped stitch. Now grab the bar of the stitch right above it in the crook of your crochet hook. Pull the bar through the stitch.
music in video is from demo 2008 by (Latch\xe9 Swing) / CC BY-NC-SA 2.0. This video knitting tutorial will help you learn how to pick up a dropped knit stitch.