my clock has stopped on my macbook pro?

Lizzy ~ Welcome to the Support Communities. What version of OS X is your Mac running? ...Click on the  menu at top left of your screen and choose About This Mac. Under OS X, note the version in the form 10.n.n and then see this ASC tutorial:

Update your product list

For the clock problem, try this:

1. Click on the  menu at top left of your screen & choose System Preferences...
2. In the panel that opens, click on Date & Time.
3. In the resulting panel, you may see three tabs at the top — click on the Clock tab.
4. In the resulting panel, uncheck "Show date and time in menu bar"
5. Check "Show date and time in menu bar"

...When you point over the clock, does the color wheel still appear?