Knitting mistake

I forgot to wrap yarn around the needle for one of the stitches, so it’s missing that ‘bump’ you see when you make a purl stitch. How can I fix it? Are there any videos I can see?

If you have skipped a stitch, you can work across the row to that stitch and then use you needle or a crochet hook to pick up the yarn in the row below that is connecting the 2 sts on either side of the skipped st, put the bar of yarn on the needle and use it to work the st (either knit it or purl it). The st may seem a little tight, but it will ease out and the tension will distribute along the other sts.
See if the videos under the Free Videos tab at the top of the page, Tips, Fixing Mistakes, Dropped st or Correcting a mistake help. They’re not exactly your situation, but close.