Go to the Menu, option and then cheat
finally press enter:

GIMMEALL - All levels and cars active.
RESETALL - Reset to game defaults.
RESETLAP - Record laps and times reset.
KEYFOUND - Found all padlocks keys.
RESETFMV - All films reset.
CINEMAON - All films available.
RESETKEY - All keys reset.
KARTSON  - Game with Karts.
KARTSOFF - Game with no Karts.