Sometimes it becomes necessary to reset or reboot a misbehaving Macbook. Here are a few ways of resetting your laptop and some of it's systems. This list covers restarting and rebooting your laptop as well as resetting the PRAM (Parameter RAM) and the PMU/SMC(System Management Controller/Power Management Unit).
Tap the power button
On newer laptops you'll press the Control + Eject key. When the dialog box pops up to restart the computer, click on the Restart button.
Press and hold the power button
If your laptop freezes up or becomes unresponsive, you can reboot your laptop by pressing and holding the power button for a few seconds. This will power down your computer so use this option as a last resort. Any files that were open at the time or files that you were working on could be corrupted by doing this. Once the laptop has fully powered down, you can press the power button again to start it up again.
Command + Option + P + R
This will reset your laptop's PRAM (Parameter RAM). If you are experiencing issues with some system settings that don't survive a reboot or if you see a question mark briefly when restarting your laptop, it may be necessary to reset the PRAM.
Resetting PMU/SMC(System Management Controller/Power Management Unit)
Apple provides some tests that should be performed before proceeding with a PMU/SMC reset.