At my work somebody that is not familiar with Magento did strange changes that affect my site badly, is there any way to reset last changes.? As example: cancel the changes in last 24 hours
This is not possible as a feature. You can however request a database backup from your hosting provider and overwrite your database.
Please note that all orders are lost as well in that case. A partial backup might also be possible where you leave the old
customer_* tables and replace the rest.
Also, make sure to always keep the
eav_entity_store intact. The order increment ID is stored there and resetting that to a previous one will most likely cause fatal issues with your Payment Service Provider
If you run backup everyday then it is possible.
var/backup folder if you have any backup or else you can ask your server provider to see if they do everyday backup.
In dedicated server, server provider set
image creation everyday, so that you can re-install server with that particular day's files.