Roxas's memory loss...

[JustSnilloc]

Was it ever explained why exactly Roxas lost his memory before he started living in the data-twilight town?

He seemed to remember everything perfectly fine (Well, not everything, but...) before his battle with Riku... Did DiZ do something? Did Riku hit him on the head a little hard? Did Xion have something to do with it?

I can't seem to recall that ever being explained, so I thought I'd ask

 

[Youniquee]

DiZ probably erased his memory for conveniency. If he still remembered things about the Organisation and Axel, Roxas would try to escape and cause trouble for them, therefore hindering Sora's restoration process. Besides, he'll also know that he was trapped in Data-twilight town before the time was right, yes?
I don't think it was fully explained either, but this is just my take on it.

 

[Sephiroth0812]

DiZ ordered Naminé to alter Roxas' memories, essentially brainwashing him in order to keep him from rebelling and also to throw the Org off his tracks.
That was also a reason why Roxas smashed the computer in anger once he regained his memories, as he realized that he was kidnapped, brainwashed and again only used as a tool just like the Org had done before.

 

[CaptainMarvelQ8]

That was also a reason why Roxas smashed the computer in anger once he regained his memories

I've always thought he did that out of frustration of being so confused

 

[bladewarrior13]

I don't think it was fully explained/confirmed, but its pretty much true that it was DiZ's doing (having Namine erase his memories) especially considering near the end of the game when DiZ/Ansem dies he says "And Roxas, I don't know if you can here me, but I am truely sorry."

 

[Key Wielder]

On the sixth day when Roxas begins remembering everything by the computer, we see a flashback from right after Riku kidnaps him. DiZ explains the necessity for erasing his memories there:

"He holds half of Sora's power within him. In the end, he'll have to give it back. Until then, he'll need another personality to throw off his pursuers."