Seems like there's a glitch on the PSN at the moment where the games list has vanished for the Welcome Back content. If it applies to you, here's the fix c/o the Sony Blog:
I no longer have the option to choose my free Welcome Back games. What can I do?
If you navigate away from the Welcome Back section of the store without choosing your free games or exit the store completely you may need to follow the below in order to choose and download your free games. On your PlayStation 3 or PlayStation Portable navigate to the PlayStation Network icon on the XMB Log into your PlayStation Network account and choose Account Management > Transaction Management > Services List Choose "PlayStation Network Promotions" from the list of services displayed Select either "PS3 Free Games" or "PSP Free Games" and then choose "Select Content"
You will be taken to the store to choose your remaining free games.