From PHP version 7.0 mysql functions are deprecated. It is recommended to use mysqli functions for PHP version 7.0+
SOLUTIONS:
- Please enable mysql functions module from PHP extensions in CPanel
- Install mysql module if you are using VPS
- Start using mysqli functions rather than mysql functions
- Change your PHP version to 5.6 from 7.0 (Not Recommended)
Source:
Call to Undefined Function Mysql_connect()