November 22, 2018 9:13 EST PM
The two obvious "reset" steps you could try are SMC & NVRAM - as per these generic instructions pasted below:
1) SMC reset - laptop (2 minutes)
• Shut down the computer.
• Plug in the MagSafe power adapter to a power source, connecting it to the Mac if its not already connected.
• On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.
• Release all the keys and the power button at the same time. (Do this a couple of times if you're unsure.)
• Press the power button to turn on the computer.
Note: The LED on the MagSafe power adapter may temporarily change colour or turn off when you reset the SMC.
2) NVRAM reset (2 minutes)
• Shut down your Mac.
• Locate the following keys on the keyboard: Command (⌘), Option, P, and R. You will need to hold these keys down simultaneously in step 4.
• Turn on the computer.
• Press and hold the Command-Option-P-R keys before the gray screen appears.
• Hold the keys down until the computer restarts and you hear the startup sound, or see the big Apple icon, for the second time.
• Release the keys.