Missing a stitch

How do I correct myself if I miss a stitch?

There’s two ways that I know of that you can do this

frog it til you think you have the stich you missed or make another stitch on the new row. But if it’s like in the middle of the row and you can see it it’s best to frog

Do you mean you have too few stitches…as in you need 40 and you have 39? Or did you miss knitting a stitch? If you need one more just increase one stitch where it will show the least. It won’t show in the end. If you forgot to knit a stitch you can fix it if you haven’t gone too many rows. It’s similar to fixing a dropped stitch.
Scroll down to fixing mistakes here;

Or look here;

If it’s something else please explain again.

i agree. if you mean you just misse a stitch while counting you can go ahead and add one. if you missed it like droppedd it in your work you can correct it.
go down on fixing your mistakes and second link of dropped stitch