As you have a flashing question mark in the folder the system is looking for the system files (Reference: About the screens you see when your Mac starts up). So either the drive has been removed or they completely formatted the drive but failed to install the OS back on.
So... Where does that leave us? Assuming the drive is still present then you'll need to find a friend with a Mac and then either connect to his Mac back to back so you can leverage his system to prep up your internal drive.
We call this Target Mode and here is Apple T/N that explains how to set it up: Share files between two computers with target disk mode and as additional reference: Startup key combinations for Mac.
So here we'll interconnect your friends system and from it run Disk Utility. From within it, it should see your systems drive if not the drive was removed (let us know if that is the case). You'll need to format the drive and setup a GUID partition map and then create a Mac OS Extended (Journaled) partition. Once this is done you'll run the OS installer which your friend may need to download from the Apps Store for you.
If you can't interconnect your system with his you'll then need to prep up a USB thumb drive (16 GB) using his system here we also need to delete the FAT volume and reformat it using Disk Utility as we did above. Then run the OS installed to install the OS onto the thumb drive. You'll need to copy over to the thumb drive the OS installer as well. Once done you'll use this thumb drive as your boot drive and basically repeat the operations again.
Update (11/03/2016) CORRECTED
Here is the IFIXIT guide for your systems hard drive: MacBook Pro 15" Unibody Mid 2012 Hard Drive Replacement You may also need to replace the drive cable as well here: MacBook Pro 15" Unibody Mid 2012 Hard Drive/IR Sensor Cable Replacement as they often breakdown.
I would recommend going with either a 2.5" hybrid drive (SSHD) or a SSD if your drive is missing: Seagate laptop SSHD or a Samsung 850 EVO
Your system also has two fan units so the noise you here could be a dirty fan or the bearings are going on one of them.