From this point onwards, any photos that have been imported into Lightroom should be managed using Lightroom and not your operating system.
Did you really delete the folder with the originals? Don't you have duplicate copies or backups? Are the photos still on the camera card? Can you find the original photos in the trash?
If you still have another copy of the originals somewhere, just re-create the folder in your operating system (with the exact same name as before and in the exact same location as before) with the original photos in it.
If you don't have another copy of the original photos somewhere ... well, let me suggest you begin making regular and automated backups of your photos, no excuses ... and download something called an "undelete utility" (there are free ones available) to see if it can recover your original photos.
Last resort ... well try those things first ...
What you are seeing in Lightroom are the previews that were generated. But the images are done because you deleted the folder. Images are never "in" Lightroom. They are in folders on your hard drive. It would be wise to import the images to a folder structure where they can reside permanently. You don't want to delete images or folders of images just because you have exported them. Exported copies are to be used to share with others through e-mail or posting on the web or to send to a lab to be printed. But you always want to keep those images.