Forgot the local admin password ? If you don't have any other chance try to recover it. There are some ways to recover a password, I found a safe and quick tool to perform this hack job... the NTPWEdit tool loaded in a bootable USB key.
NTPWEdit is a free tool ( GPL ) that allows to change or remove passwords for local system accounts. This tools supports Windows NT based systems (like Windows 2000, XP and Vista), but could be used also to reset the password of a Windows 7 systems.
Some methods for use this program:
1. Boot Windows PE or BartPE environment from CD-ROM and launch NTPWEdit.
2. If system partition formatted in FAT filesystem - boot DOS from floppy disk, copy SAM file to floppy, edit this file on another computer and copy it back.
3. If system partition formatted in NTFS file system - copy file using Windows recovery console.
4. Attach hard drive to another computer, and edit passwords there.
5. Boot system from separate partition (if multiple OS are installed).
Link : NTPWEdit version 0.3