Keyboard and Mouse Non-responsive

[APseudoUtopia]

Hey,

I have Ubuntu 9.04 on a Laptop. I was playing around with aptitude and
removed some packages that I didn't think I needed (I know, I
shouldn't have...). I rebooted, and now both the keyboard and mouse
are unresponsive. It boots up fine, and displays the login screen. The
cursor on the login screen is blinking (so it's not frozen up). But
the mouse is entirely unresponsive, as is the keyboard.

Does anyone have any ideas as to how I can fix this?

Thanks.