Deleted Folder.

If you are using an SSD, then those files are gone unless you have a backup or another copy stored elsewhere.

Even if you are using a hard drive retrieving the data is difficult and you need to immediately power off the computer. You need to either boot from an external drive or put the Mac into Target Disk Mode to connect it to another Mac where you can attempt to use data recovery software such as PhotoRec, TestDisk, or Data Rescue. Be prepared for finding tens of thousands of unnamed files which you will need to sort through. Even if you can sort them by general file type you will still be sorting through thousands of files.

You can also contact a professional data recovery service such as Drive Savers or Ontrack. Both vendors provide free estimates and both are recommended by Apple. Even with a professional service you will likely need to sort through thousands of unnamed files. You still need to immediately power of the computer so you don't accidentally overwrite the files you are looking for.

If you have a TimeMachine backup, you can recover what was in the folder since the last backup