Q: Does restore erase files

You do not need to reinstall OS X if you have forgotten your administrator account, because this can be resetted.

First of all, try resetting your user account password with your Apple ID > http://support.apple.com/kb/HT1274

If it does not work, reset the password in OS X Recovery > http://discussions.apple.com/docs/DOC-4101

If you want to reinstall OS X because you have forgotten your user account password, the only way to get rid of it would be to format the hard drive first, so you will lose your files

Hello, it should not, but...

Reset Password 10.7, 10.8...

http://reviews.cnet.com/8301-13727_7-20087723-263/how-to-run-the-password-reset- utility-in-os-x-10.7-lion/

Then Reset your Keychain...

http://support.apple.com/kb/TS1544

http://www.macyourself.com/2009/08/03/how-to-reset-your-mac-os-x-password-withou t-an-installer-disc/

When you set up your Mac did you choose the option to allow resetting your Admin password using your Apple ID ?

I've never tried this.. but in theory this might be an option..