dropped stitches are not the end of the world. Just pick them back up and fine.
if a stitch slides off the needle: just bring the tip of your needle back trough it. In worst case you have twisted the stitch in doing so (I do that all the time). Then you can just move it around by lifting it off and back on (knit- and purl-wise) to untwist it. you will see.
If you have a stitch run down several rows... well, that is a little worse. But not so bad (if you are not doing lace, anyways)
the stitch then leaves a trace: sting spanning across the line of the stitch.
just take your knitting needle (or better a crochet hook, my favorit weapon in this case) and lift the stitch back up, row by row.
In stochinette: if you work this from the RS: slide the hook trough the stitch from front to back. Pull the "spanning yarn" through to the front. Continue this way for all rows.
In garter stitch:
row 1 you do like that (above) then the next (row 2) you do with the spanning yarn in the front and the hook going through from back to front. Just try one stitch and see if the result is what you want, if not: start correcting with doing a row 2 first.
keep alternating untill you have all stitches back in place.
In case you should have a massive desaster (say you travel with your knitting and several stitches drop out, fall down and make a big mess)... there are different ways to fix it: rip the piece out to the point of no damage (depending how many stitches fell and how much work the fixing in the other way would be compared to re-knitting)
or: secure all individual stitches before starting the fixing. You do that by putting something in the loop to prevent it from slipping lower.
you can take knitting needles, crochet hooks, waste yarn that you thread through with a wool needle or crochet hook. You can use safety pins, openable stitch markers... whatever. The goal is to make sure that the loop does not slip through the loop below.
When securing stitches: try to pull on the yarn as little as possible. That makes the next stitch slip.
Then you can fix stitch by stitch.
What I want to say: We have all dropped stitches. We have all survived. I do not know of acutal suicide because of this.
If you still are afraid: check out "life lines". They put you at relative ease with the thing. Messing up or dropping stitches really is not so bad with a life line.