Hello,
( i've post that message on the general discussion but apparently it is not the good forum, so we say to me what the spoilers forum is the good)
First sorry for my english, i'm not of an US or Uk country and so, english are not my first language .
(sorry for not tell my nationality but my country are one of them who are the most critic)
(P.S.: I don't use the traductor because the traduct are generally wrong or don't tell the same thing)
So, i've a big Problem with the thieve's guild, before ou after the mission on lumidor/luminor house, Mercer give at us the first thieve's armor .
At this moment, i've sold that item .
Big mistake ....
Later i've entierrely complete the missions (secondary or principal) of the thieve's guild, now i must go take the master thieve's guild .
But tonalia, want firstly my first armour of the guild for upgrade that, but like say previously, i've sold that item, entierely .
I've search everywhere in the thieve's base, talk to the merchant who have buy this item, search in the net, in the official help book. but nothing, i don't refound that .
So i send a message to bethesda, but they answer to me what they are entierely recover of request and what i must gone to the official forum for request my question .
So, if someone have an good answer please help me .

once again, sorry for my bad english

• This armor is needed to exchange with http://elderscrolls.wikia.com/wiki/Tonilia in a later quest. Without it, the quest cannot be completed and you're unable to use her as a fence. Additionally, you will not be able to finish http://elderscrolls.wikia.com/wiki/Under_New_Managementand become guildmaster if you do not have the armor.

For the above reasons do not under any circumstances sell your Thieves Guild Armor back to Tonilia or any other merchant as there will be no way at all to retrieve it. One can add the armor to their inventory on the PC version using the console, but so far there is no known fix for the PS3 or Xbox360 version.

http://elderscrolls.wikia.com/wiki/Thieves_Guild_Armor

Guess you have to start a new game. Sorry

You already have http://www.gamesas.com/topic/1341057-refound-the-first-armour-of-thieve-guild/ on this

OP, moved your first thread to this section so you could get an answer. No need to create a new thread. Use the one that is linked above that you created earlier.