Remind a user about their account if they have not used it for 6 months

Take a look at the Transients API. It’s meant to store data temporary. Note, that this doesn’t replace a cron job, as it needs “Action” on the site. So if the site isn’t requested, where you set/alter/delete a Transient, then nothing happens.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)