So far I've had:

2h weapons, got way too easy
Archer (favorite) far, far too easy
Thief/assassin, quickly got dull

I need something to do in this game. I don't want to stop playing, but I'm starting to run out of things to do. Companions, Thieves, DB, Main... I've done them all multiple times. Help me out please.

Have you done a magic specialist yet? Conjuration, enchanting, alchemy. I've always favored magic specialists in RPG's. I just find fighters to be boring.

I've never done magic in RPG's. I don't understand it. You can use spells, but once you run out of mana you have no form of attack, it's like a quiver with no arrows :/

If you didn't run out of magicka though you would be practically invincible. There has to be some kind of limit. I agree you should try magic, I mostly play warriors myself but magic is a part of the game that would be a shame to never experience.

You manage your magicka the same way you manage your stamina- you don't blow it all in one attack, right? Use conjuration to call up an ally with magicka of their own. While the enemy are fighting them, burn them down from behind. You can also use illusion to sneak past multiple targets and position yourself better. Use wards and armor spells to lessen the damage you take, and throw down runes to catch the enemy as they rush you.

Magic is a lot of fun if you dabble in all of it- specializing in just one tree isn't a good playstyle. Play with everything!

Magic is good. Just get fortify (insert magic you use) enchantments so you don't run out of magicka. If you prefer melee maybe Hand 2 hand, or sword and shield?

Let me ask this.

Currently my character is level 28 with the skills below. If I put the bow away for a little while and start doing magic with this character (destruction and conjuration... restoration?) will that ruin my character?

Archery: 86
Light Armor: 40
Sneak: 47
Lockpicking: 31
Pickpocket: 22
Speech: 24
Alchemy: 20
Illusion: 20
Conjuration: 50
Destruction: 26
Restoration: 18
Alteration: 20
Enchanting: 62
Smithing: 73
Heavy Armor: 17
Block, two handed, one handed: 15-18

You could always try using bound weapons. Adds in some magic flavor, but keeps the basic essence of the character.

Go for:
pure mage, specialising in destruction/necromancer/illusion etc
Impact is OP btw, but once u reach the higher lvls, destruction will be underpowered, badly. But impact still keeps u alive. Just stock up mana pots

A character I had alot of fun with was a Breton, magic/one hand hybrid. I used maces, and mostly destruction/restoration and only wore robes. Ended up being a priest like character. I would start with destruction from a distance then when the enemy closed in, switch to mace and healing myself. Turn undead came in handy when clearing out dungeons so I wouldnt get overwhelmed with damage. Did the college quest line and as many "good" or "holy" quests I could.

You say you want to try something different and that the styles you've played make it too easy. Give magic a try as others have said. Conjuration is fun and if you find some staves it will help if you run out of magicka and/or potions.