If I shave my head will my hair stop shedding and grow back in as it was before the hair loss?

Plucking or shaving lab mice is a way to make them grow more hair!
But not in humans. However, when shaved or growing after a shave, it MIGHT seem thicker, since the cut edge of the hair is not tapered as the natural uncut tip! Whatever you might do on tour hair shaft is irrelevant, the shaft is dead (has no metabolism!). The issue is the root. You need to consult a specialized physician to tell  you what are the options, and honestly, there are some which are effective and will grow most of your hair back!

Unfortunately, shaving will not do much to prevent future hair loss. The problem does not lie within the hair just on top your head per say but the follicle underneath. For many, hair loss is hereditary. Dihydrotestosterone, or DHT, is a derivative of testosterone and is what has been found to cause hair loss in both men and women. About 50% of men and 20% of women have this defect one one of our hereditary genes which overproduce this. As a result, high levels of DHT leads to problems such as hair loss and balding.
However, there's also other causes of hair loss such as stress, diet, trauma, and some medications.The number one first step I recommend is a comprehensive consultation with a hair regrowth specialist who will perform lab tests to determine the underlying cause of your thinning. Without labs, no-one can really know what your true cause is and any treatment will be temporary at best. From here, you can receive the best treatment for your case.