why my Mac. restarts frequently and abruptly ?

naqi129 wrote:

Why my Mac restarts frequently and abruptly?May be kernel problem and how can I download the system or refresh it?

Work through this Help Topic:

If your Mac restarted because of a problem - Apple Support

Please post a few of the most recent Panic reports.

Look for the Kernel Panic reports at:

Finder -> Go -> Go to Folder -> /Library/Logs/DiagnosticReports

<http://support.apple.com/kb/ht2546>

<http://support.apple.com/en-us/HT200553>

The panic report should have ".panic" in the file name.

You can use the "Additional Text" box when you Reply

In addition to the above suggestion, ensure that you have a complete and current backup. One of the causes of unexpected shutdowns is failing hardware. Run Diagnostics or Hardware Test.

Boot into Safe Mode and test.

Remove the add-on anti-malware, add-on anti-virus, add-on cleaners, add-on VPN clients, and add-on firewalls and optimizers per the vendors’ instructions, reboot, and test. Various of these tools have caused corruptions, performance degradation, hangs, and crashes.

If you want us to look at this in more detail, please post the EtreCheck data here. Open a new reply here and then press the button that looks like a printed page to get a text input box big enough to paste the entire hardware and software configuration report into your reply here.

But absolutely have current backups.