Hi there,
so you droppped the whole database?
In that case you need to restore your database from a valid backup.
I hope that appropriate backup jobs where setup before, either native or through a 3rd party backup software which may is in use.
If your SQL Server resides in a VM and the whole VM is backed up from time to time than you may extract the data and log file of the database from there as well.
But keep in mind: data loss is inevitable (time gap between last succesful backup and drop command).