(The file access/creation date shown in your operating system is unlikely to be the EXIF image creation date.)
But make sure you browse all of the metadata in your image file in case you're simply not using software which reads all of the data available.
If your software truly is editing or deleting the creation date in your photo metadata then you're unlikely to find any way to recover it. In theory it's possible to embed data (usually a copyright watermark) inside the image data, but a professional photographer is unlikely to use this method in the master file because it does (subtly) alter the image and because the data degrades every time the image is retouched. Data can be added, edited, or removed without affecting the image data.
Photo metadata, such as EXIF metadata, is written into a RAW, TIFF, or JPEG file in a data section which sits alongside the image (pixel) data.
