Help - I think I might have hurt my snail

Hi folks, Last week I got my first ever mystery snail. He was thriving in my tank as happy as anything, but sadly it was short lived as I have hurt the little guy. One day I couldn't see him anywhere so I lifted the glass lid and seen he was up in the corner by the filter munching on some plants or something. I clumsily put the lid back down but it bonked him and he fell to the bottom of the tank. His shell is not cracked but he hasn't been the same since :( and it makes me so sad. Now he spends a lot of time upside down like in the picture below. He does move about ever so slightly and I do see him appear in other places but he might be in this upright position for many hours before moving and hanging on the back of a leaf in the same spot for many hours. Is he dying do you think?