Try " pick up dropped stitches" for your Google search. I could maybe try and explain how to do it with a crochet hook, but YouTube will probably be more helpful.

When a stitch is sitting the right way on your needle, the right "leg" of the stitch will be to the front. (When you look at a stitch head on, it has a left and right side. Right side is closer to you on the needle.)

I hope this helps! Dropping stitches the first time is terrifying. It gets easier, I promise.