Using the /cleanviews switch will restore your default views.
Using the /firstrun switch will start Outlook as if it were run for the
first time.
Start > Run > outlook.exe /firstrun
Start > Run > outlook.exe /cleanviews
(note the space between outlook.exe and the switch)
If you're using Vista or Windows 7:
Start > Start Search > outlook.exe /firstrun
Start > Start Search > outlook.exe /cleanviews
(note the same space after outlook.exe)