Wow, Ty, that's a real bummer. Luckily, I make sure my wife has my passwords and just don't do anything I don't want her to see.
Yeah, RumoredNow is correct. There is no way to recover a lost/forgotten password on Windows Phone.
Fortunately, you can reset without losing the data on your SD card. Anything saved on the local phone storage will indeed be lost, unless you have a cloud backup of it already.
This is a sad reason to join us needing this type of help, but, for what it's worth, welcome to the forums! Stop by our
Introductions forum and introduce yourself, and we'll make you feel right at home. You've come to the right place to learn all about Windows Phones, and you might need more help when you upgrade that 640 to Windows 10 later.
Wish we could have been more help, but that's pretty much the state for all of today's smart phones. Make sure you remember the password well the next time. Here's a hint. If you sit with your phone and lock/unlock the phone about 30 or 40 times in a row in fairly rapid succession, you'll pretty much have it memorized for life after that.