You may find it annoying and waste important work time if your MacBook is stopped at the loading screen. To resolve this problem, though, there are a few options you can attempt.

Frequently Occurring Mac OS Issues

• Flashing Question Mark Folder
• Fails to boot properly 
• Not able to enter Mac OS 
• Very Laggy while using 
• Stuck at apple loading bar

Correction & Solutions

1. Safe Boot: When your MacBook boots up, hold down the Shift key to boot it in Safe Mode. Safe Mode can assist in isolating the problem by loading the bare minimum system requirements.
2. Reset NVRAM/PRAM: You can resolve the problem by resetting the PRAM (parameter RAM) or NVRAM (non-volatile random access memory). To accomplish this, turn off your MacBook and press and hold the Command, Option, P, and R buttons at the same time until the device restarts.
3. Repair Disk: To fix any disk issues, use Disk Utility. To accomplish this, when your MacBook is booting up, press down the Command + R keys to enter Recovery Mode. Next, launch First Aid by selecting Disk Utility.
4. Reinstall MacOS: You can attempt reinstalling MacOS if the aforementioned fixes are ineffective. Choose the option to reinstall MacOS when you boot your MacBook into recovery mode.
5. SMC Reset: Resetting the System Management Controller (SMC) may also assist in resolving the problem. In order to accomplish this, turn off your MacBook and press and hold the Power and Shift buttons at the same time for ten seconds. Click the power button to turn on your MacBook.

One by one, try the aforementioned solutions until you find the one that works best for you. Before attempting any of these procedures, don't forget to make a backup of your data, as they can cause data loss.

If none of the solutions listed above resolve the problem, it might be a hardware one. For a diagnosis and repair, get in touch with Apple support or an IRepair Service Center.