By "prostate problems" do you mean benign enlargement of the gland (prostatic hyperplasia)?

Saw palmetto (Serenoa repens) is probably the best known and studied herb in this regard, and has shown some effectiveness in helping urinary symptoms (prevention of benign prostatic hyperplasia by intake of this herb is less well-characterized, as far as I know).

There is also preliminary evidence that lycopene (found in tomatoes) may prevent as well as treat prostate cancer. More here.

In the U.S., problems with standardization of herbal medicines mean that you can't be sure that a given supplement contains significant active ingredients - and this has been shown to be the case for saw palmetto.

You could try nettle root.

Try this.

Mince 500 g of pumpkin seeds and mix with one cup of honey. Make little balls ( 2cm) and keep them in a fridge.
Take one daily ( put in your mouth and resolve it)before meal.
Do it only once a year.