Data is stored on HDD's a bit like the way 'data' is stored in a library.
There is the actual data itself which corresponds to the books on the shelves.
And then there is the index system that tells the OS where that data is located which corresponds to the libraries card index of the books on the shelves.
When data is 'deleted' the data itself [the books on the shelves] is generally not touched.
What actually happens is that the index system is edited to tell the OS that the part of the HDD where the data is stored is now free to be overwritten... But the data itself stays there until such overwriting takes place.
This has two benefits, one it means that your HDD will last longer and work much faster than if it actually had to manually scramble all the data every time you deleted something. And two, it means it's possible to recover the data AS LONG AS YOU DO DATA RECOVERY BEFORE OVERWITING HAPPENS. So, if you have 500GB worth of music that you would like to get back, as long as you have not yet overwritten that data by using the HDD it should still be there and recoverable.
My recommendation would be to take it to a reputable company that offers data recovery to do it for you, however that will obviously cost, and you may not be prepared/able to pay for that so... Here's how you can do it yourself.
First you need some [free] data recovery software to search the HDD for data files that don't have indexes pointing to them. [I would recommend 'Recuva' from piriform the same company that provides ccleaner https://www.ccleaner.com/recuva as this is easy to use and from a reputable company, but you can check out reviews and decide for yourself. Free software will never be as good as the expensive pro-stuff, but will probably do in this case] And you download and install this software ON A DIFFERENT HDD/SDD FROM THE ONE YOU ARE DOING DATA RECOVERY FROM. Because you do not want to do anything that might possibly overwrite the data you are trying to recover.
[as a side note, this is a good reason for already having this kind of software installed, so if you accidentally delete/loose something you can immediately run data recovery and not have to worry about how to install without overwriting the data you have deleted/lost. Alternatives are to have it installed on an external drive or usb penstick]
You will also want at least as much free storage space on a storage device NOT the one you are doing data recovery on to hold ALL the data you are trying to recover. You will need to copy that data off of the drive you are trying to do recovery on before you can restore it. [a decent size external HDD is your friend here, particularly as you have 500GB+ you want to recover]
Having got all that setup, you can then run the data recovery software on the offending drive, and look for the lost files. You can filter by file type so you can just look for pictures [or media files in this case] if there is a specific thing you are looking for.
However this search will turn up everything on the HDD that matches that file type that has been deleted and while you can hopefully recover most/all your lost files. You might well also get a bunch of duplicate/corrupted/partial files as well... In short what you get back is likely to be a mess. So resign yourself to many hours of sorting it out and tidying it back up again. [and you might not get everything back, or even anything, depending on what you have done to the HDD since this happened]
Good luck.
And invest in some decent multiply redundant backups. I recommend using Backblaze for automated secure cloud backups, and then additionally running manual backups to external HDD/Penstick.