Can you drop your flaps? If you can then you should be slow enough to lower your gear. I would check to ensure the G isn't damaged (Ctrl-D) or that you have your key-re-mapped just to be sure next time (Go into Setup, Keys, and check the gear, I think it's under flight-settings or something).
Never heard of not being able to lower gear. I fly the B-26 quite often myself and I've never had a problem unless I'm overspeed (over 200mph) in which case it won't let you lower them for fear of tearing them off.
-Soda
The Assassins.