These are knit flat? And what happened is that the last stitch on the row fell off before it was knit and is sitting there as a stitch loop? Is that right? If so, yes, just stick your left needle back in the stitch and knit it. Then proceed to do the cast on however you intend to do it.
Ideas for the cast on if you don't know what to do: You could use a Single Cast on as given in the videos. You would do that at the end of the row, just throw 5 more stitches onto the right needle at the end of the row. Or.... turn and use a knitted cast on, or cable cast on. This will, in effect, put the stitches at the end of the row, since the end of the row and the beginning of the next row are the same place really.
Knitting can be frustrating sometimes. It isn't always smooth sailing and totally relaxing. We all make mistakes and have challenges. Take a break if you need to. It will help you if you can learn to fix mistakes, but in some cases that means tinking back or ripping back. There is not a quick and painless fix for everything, even for the experienced knitter. Hang in there.