Hey man, not sure if this will help you, or you've tried this, but it's worth a try I'd imagine. I saw someone post it on another forum where people were expressing your problem.
Q: I no longer have the option to choose my free Welcome Back games. What can I do?
A: 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.
1. On your PlayStation 3 or PlayStation Portable navigate to the PlayStation Network icon on the XMB
2. Log into your PlayStation Network account and choose Account Management > Transaction Management > Services List
3. Choose “PlayStation Network Promotions” from the list of services displayed
4. Select either “PS3 Free Games” or “PSP Free Games” and then choose “Select Content”
