So I go on ps3 to play Skate 3, and my PSN won't let me sign in. **bleep** awesome. Then when I go to reset my password, and I enter my DOB, It says it's wrong. Then when I try to sign in with my new account (this one) It says that I cant use another id. **bleep** GOD SONY STOP BEING **bleep** **bleep** TO YOUR CUSTOMERS!
About your other thing, it's not sony's fault that you used a false birthday, infact, it's even against the rules to provide false info.
Chaos_789 is correct you agreed to provide correct information when making your account. If indeed you did and you are still unable to access you account did you share it with any friends. Even if you didn't I would still recommend contacting Playstation for further assistance with accessing your account.
Regarding signing into your second user. You cannot sign into a different PSN account than the one that is associated with the user. Switch to the user you used to create the new PSN account and then sign in.