If you're on magento1 please check if there's no file
maintenance.flag
in your store root. If it's there - remove it.
If you're on magento2, run following command in terminal:
php bin/magento maintenance:disable
Hello @daniela_laurent
In most cases, to solve this, go to your Magento root installation, find a maintenance.flag file and delete it. If this didn’t work, clear the cache and sessions and try again.
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