Photos do not show when i transfet to sd card

[Kingkaka]

When i transfer my photos and videos to my sd card,  they show for a while but then later turn black and when i play video, it says sorry, invalid url. I dont know how to fix this issue and i have a sandisc ultra 64gb card but still doesnt show.  what is the sollution to this??? Plz plz help fast

Sometimes cannot play video or sometimes invalid url

[Qatrium]

@Kingkaka

Can you try to:

- Copy all your SD card content to your PC

- Format the SD card from inside your phone (Settings -> Stotage & memory -> tap on the 3-dot icon -> Advanced -> Storage -> SD card -> tap on the 3-dot icon -> Storage settings -> Format)

- Copy back your files to SD card