The lesson I learned just like you is to upload the pictures more often. In the camera all it takes is one glitch and they are gone.
Try one last thing. Unplug the card and try the camera without the card. Just in case your camera has onboard storage. (I didn't find a make and model of camera and cards in the post.)
Some Ebay memory cards are fakes and weird things like this happen.
Parting tip. Be sure to format your memory card IN THE CAMERA when you put in a new card and maybe once or twice a year to keep the file system clean and happy.
I went on a trip two weeks ago and took many pictures which I saved on my memory card. I then went on another trip this past weekend and took more pictures on the same card. After the first trip I was able to playback the photos on my camera with no problem but today when I tried to upload them to the computer, only the pictures from the second trip showed up. I can't access the pictures from the first trip on my computer or on my camera. I have tried several free photo recovery softwares but none of them have recovered the pictures. Does anyone know what could have happened to them or how I can get them back?