How did Robin come back?

[eledoremassis02]

After he ran away, Two-Face and Riddle attack wayne manor and then Robin shows up with the Robin suit?

I assume when Bruce was out Alfred was able to find him, but was it explained anywhere?

[The Laughing Fish]

You might be forgetting that Alfred mentioned that he made the suit for Robin when Batman asked who made it for him; just before they go fight Two-Face and Riddler together.

[The Laughing Fish]

Ah bloody hell, I just read your question carefully again and I now realize my answer wasn't what you were asking for. 

I think it's simply nothing more than Alfred getting in touch with Dick immediately after the attack on Wayne Manor. That's pretty much it.