Lost password on my MacBook Air
Reloaded OS 10. Now sign on password does not work
MacBook Air, Mac OS X (10.7.5)
Which OS version did you "reloaded?" Your system profile confirms you are using Leopard (Mac OS X (10.7.5)). Yet, you posted in the Snow Leopard forums.
Need clarification to provide the proper troubleshooting suggestions. In the meantime, see KB Article: http://support.apple.com/kb/HT1274Changing or resetting an account password