SQLSTATE[HY000] [2002] Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock'

After a power failure on my FreePBX CentOS system, I rebooted it, but now FreePBX doesn’t start and displays this message. Please help me recover all settings of FreePBX as I don’t have any backup file.

mysql Ver 15.1 Distrib 5.5.65-MariaDB, for Linux (x86_64) using readline 5.1
freepbx.x86_64 14.1-1.sng7 @anaconda/2011