Photos and videos are time and date stamped by your camera when they are taken. Sometimes when the photos/videos are not loaded onto the date we expect them, they can be located on an earlier date because our camera's settings are off.
Please look through your site to see if the photos/videos you are looking for are on a different date. Also, check your camera settings to make sure they are correct.
To correct the date of the photo/video, follow these steps:
1) Click on the photo/video
2) Place your cursor on the date/time stamp beneath the bottom left corner of the photo/video
3) When it turns blue, edit the date/time stamp and press ENTER