If it’s not in the recycle bin, I’m afraid it’s gone. I also did such a mistake in the past. I’d recommend not deleting your assets from your PC after importing them to your project.
Additionally, I’d recommend connecting your project to a version control system since it’s a must have even for small projects. However, only relying on version control to save your progress is still not safe, as reverting might not fix certain issues or you might not be able to revert at all! For that reason, you should also manually backup your project and keep the backup(s) in a safe drive.
Hope these help! 