No bank managers key in the drawer of the bank in story mode.

[Proton Decay]

How do I fix it?

[IFIYGD]

Check your Journal (not your backpack), to see if you had not already picked up the key (if you looted the credit Union before knowing the location of the house key from whichever guide or walk-through you are using). If you already looted the bank managers house (the one with the Canadian flag at the porch), you may have already unlocked it. without knowing you needed to go there to find a certain item (Bank Vault Code) from the quest Grey Mother gives you for the safety deposit boxes.

If you have not looted the Credit Union before, and you have not unlocked the Bank Managers House,and the key is not in the middle desk drawer- verify game file integrity to make sure you have no missing or corrupted files, make sure you are using an up-to-date guide or walk-through for the Redux version (not one from the original version of Wintermute), and file a bug report if the key is still missing and the house is still locked: https://hinterlandgames.zendesk.com/