I'm a newbie & while trying to rename a photo I accidentely hit override photo which deleted a photo I wanted both on my phone & pc. Is there any way to recover the overridden photo?
If you simply deleted the photo, it should be in the recycle bin on your PC. The BB doesn't have a recycle bin. If you overwrote the picture with another picture, it's likely gone.
If the image you've accidentally deleted was stored on your MiniSD you could always get images recovery software such as RecoverMyPhotos .. but other than that... JeffH is totally right.