Recovering your bank account PIN will depend on the specific policies and procedures of your bank. Typically, you can request a new PIN by visiting your bank branch in person with proper identification, or by contacting your bank's customer service department.
To find your PokerStars ID using the Android App: When logged into the PokerStars Android App. Click Account bottom right. You should see your Table Nickname at the top of screen showing how much playR$ you have.