1. If you deleted files in your computer, most likely the files will be sent to recycle bin. You can open your recycle bin to confirm that, if the files are they, you can restore the files by right click, and then choose "Restore Selected Files".
2. If you deleted files on external drive, or memory card, or usb drive, or pen drive, files will be deleted directly. If you emptied recycle bin, or use shift + delete to delete file, or files are big, those files will be deleted directly. In these cases, you need to recover them using recovery service or recovery software.
For recovery service, they are normally expensive. So I normally use good recovery software to do it yourself. One good example is asoftech, which is easy to use and no need technical skills. You can google 'asoftech' to look for more information.
One important thing is that do not save any new files to the storage where files are deleted, because new files could overwrite space of deleted files and make them unrecoverable.