Guys, I couldn't access play store. It keeps coming out 'connection time out'. But internet over wifi seems to be fine, I can open stock browser. In fact, I could go to google play webpages through browser. And funny thing, is when browsing apps through google play website, there is something like 'this app is suitable for Xperia X10i' (my old phone). Oh and apps that were installed in my old phone, is shown as installed in the website even though I don't have it in my S3. I don't understand why, very weird...  I use application manager find google play store app, and clear data, clear cache, force stop and restart the app, but still can't get it to work... Reboot phone also can't work... Anybody with any ideas, please help me...    Thanks.

how to delete old phone list? lol

Sorry I'm not an expert in this, but while googling I found apk of google play store, I thought I could perhaps reinstall using that?

Yea I did, clear data and clear cache of play store, still couldn't work. The account should be correct, my contacts sync to gmail is correctly displayed in contacts list. Also if I browse google play website, they mention that certain apps is compatible with my old phone (xperia X10i), so I think the account log in is working.

In any case a clean factory reset sounds a better option, I think I'll do that. Luckily I can download titanium backup free apk without needing play store.

Thanks for your help bro.