Invalid Serial code for The Sims 3 (base game)

[LilSandy95]

Ok, so I just got a new computer, so I wanted to install The Sims 3, so I started with the base game obviously. But after I downloaded it from origin (Because I registered the game on origin when I got it) and I clicked on the 'i' icon beside the game to get the serial code, and I entered that when the installer asked for it, so when I clicked continue the game said it was invalid? 

I have lost the serial code that came with the game, so I don't know if they are similar or not. But isn't some of the point by register the game in origin, that you don't need to worry about the CD and code and all that?

Please help me!

[EA_Spectre]

Have you already tried everything mentioned here?

Lost and broken DVDs and missing serial codes - What to do ? - by crinrict

How to find or retrieve a serial code? How to obtain a replacement code?