I don't know if this has happened to any of you, but I cannot join the Thieves Guild because Brynjolf will not meet me in the Ragged Flagon! I do not know how to advance from here, I even pushed him down into the Ratway, ran him into the Flagon by punching him, but he refuses to stay there and the quest won't advance. Considering the Thieves Guild is always one of the coolest parts of the Elder Scrolls games, this is very irritating and I feel like I'm not able to play the whole game.

Are there any solutions to this yet?

P.S. I play on Xbox, so I can't use any of the pc codes or whatever they are.

No solutions.. Same happened to me either restart or wait for itto be patched

There is a spot in the MQ where you can talk to him, that might reset things for you... Just a guess, but it might work.

On the PC:
Make sure you're in the Ragged Flagon. Open console (~ key) and type:

prid 20545
moveto player

He shouldn't be dead as he's set to essential. He may need to be 'reset', though. Again in the console, type:
disable
enable

That'll make him update his AI & so on, so the quest should then continue. Hope that helps.

He said he's on XBox though...

As someone else said, are you on the part of the MQ where you are supposed to find Esbern? Brynjolf will be stuck outside for that part. Complete that quest if you haven't and see what happens.

Otherwise, you might SOL.

Yeah, I already completed the main quest, the mage quest, the dark brotherhood quest, the companion quest, got all the dragon masks, got most of the daedric artifacts, bought a house, beat the empire... but Brynjolf will not move.

Yeah, sounds like you may be SOL with that character.

If you really want to do the Thieves Guild, you might just have to start a new character and make a bee line for Riften.