I installed voice over in my iPhone 3 and now it doesn't recognize the password?

It doesn't recognise my password, so I can't use my phone. And it disables the phone for 60 minutes each time I attempt to enter the password.

Reset to factory default.
Backup and Sync weekly so you can restore to a previous time without losing files, contacts and folders.

Yeah I agree, you must try a factory reset. Well in your case a hard reset as u r not able to access your phone. So just try this combination of keys:
Press and hold the Home button (big circle below the screen) and the Sleep/Wake button (on top of the iPhone) simultaneously. Keep pressing both keys until the phone shuts off and then restarts again. And as soon as the phone restarts you are done with resetting the phone. Hope you find this helpful.