So I have a helmet that increases frost damage done by 25%, i am just wondering if that also counts towards the frost enchant I have on my melee weapon, and not just my magic spells.

There are no enchantments that increase spell damage. ( aside form a few DLC items) The enchantments on weapons just deal additional damage in the form of a given element.

The only way to increase damage form spells, is to drink a Fortify Destriction potion.

Check the description of the helm again. Doesn't it read Frost resistance by 50%?

The Enchantments on armor that Fortify Destruction, or any school of magic for that matter, only reduce the casting cost.

Its a helmet from Dragonborn DLC called Dukaan, increases frost spell damage by 25%

Yes, it increases the damage of your frost spells, enchantments on weapons and Frost Breath.

Ahhh...I had no idea. You are correct.

Great info.

I don't know, but there's a simple way for you to test this yourself:

Put the mask on and see how much frost damage your sword does.

Now take the mask off and see if the damage has decreased or remained static.

That should give you your answer.