Even though i have completed the quest with the lexicon Septimus still hasnt contacted me and i am level 29. What should i do?

You did the quest before lv 15?

The Oghma Infinium is obtained through the quest Discerning the Transmudane given by Septimus Signus, who is found north of the College of Winterhold, at Septimus Signus's Outpost.

The quest will only be offered to a Dragonborn of at least level 15 or higher. However, the quest can't be started up until the Runed Lexicon is returned to Septimus;

if the Dragonborn is under level 15, Septimus will then say that he needs time to decipher the meaning of the Lexicon.

The Dragonborn will then have to wait until level 15 before receiving a letter from a courier, stating that Septimus has deciphered the Lexicon and wants the Dragonborn to return to him.

You must do a large portion of the main quest line before you receive the courier's message.

Also, I should mention the courier will not contact you if you aren't in a city or on a road, so most quests should take place in a city.

(Markath is a good place to try this, as the quests there can take up a good portion of time.)

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The problem is i have read over the net they are people at lv.70 and they have never seen the courier. (So it may be a glitch happens randomly to someone)

So you can try to clear your cache, or even re-install the main game again. (If you haven't touched any DLC's yet you can try it first without, and then with the 1.9 patch)

GOOD LUCK !!!!!