It happens to everyone. Even advanced knitters have days when everything seems to go wrong. Do you remember the first time you used a mouse on a computer? How about the first time you tried to ride a bike? There is a learning curve and it will take some time.
If you are really a beginner, I'd honestly suggest that you avoid starting with a project like a sweater. It's not that I don't think you can do it, it's just that it takes so long to complete it that it can be too frustrating to stay with it.
Try starting with something like a hat. Smaller and faster than a scarf, hats can be completed in a week if you only knit a little or a couple days if you knit a lot. There are some really fun patterns that have little to no shaping and knit up super fast.
If I might shamelessly promote my own patterns, you might enjoy making this:
It's simple, fast and cheap to make
As a note on keeping track of your stitches, try working a few rows where you count your stitches on every row. One common mistake that beginners make when working in Garter stitch is that they try to put their yarn in back when they start a new row. When you turn your work at the end of a garter stitch row, the yarn should start out hanging in FRONT of the work. If you wrap your yarn around the back you will make an extra stitch.
Hang in there and don't lose hope.