How can I change levels in Theme Hospital
Solution 1:
There are two ways to achieve this.
The first is to press C on the level advancement screen (with the board game). This allows you to click on the level you want to play. Annoyingly, it can cause the mouse to disappear, making it difficult to click the level you want.
Your other option is to use cheats. Open a message and enter 24328 on the fax machine and press the green button. This will enable cheats. With cheats enabled, press F12 to automatically win the level. Skip your way to the level you want.