Recently I had a person show me on their computer that their picture files were all there but would not open or show in thumbnail. The OPC had recently been worked on. We could copy the pictures from the PC to a usb drive and back and they worked, and she could put new pictures on the PC that worked ok.
The owner of each file had been removed on her computer. When the file is created it is given the owner of whoever is signed on the PC. Since there was no owner there was no user to match security rules with and the files could not be opened.
There are two ways to change ownership. The first you can do on a single file. Right click the file and choose properties. Then choose the security tab. Choose advanced button. Then choose owner tab and Edit in Windows 7. (in Windows 8 you will choose advanced) In Windows 7 choose Other Users and groups now). Choose Advanced in Select User or Group. Click find now. Find your user name and click OK. Now click ok on each box to close
The second is to use a command. Go to command prompt (easiest way is to type cmd in search and click cmd.exe when found. Then at command prompt change to your folder where files are. I wanted to change in the pictures folder in the user folder in the users folder so I will type cd\users\user\pictures Next type the following command to change all files to current user takeown /f *.*
The *.* says all files. If I only wanted to do .jpg files I would use *.jpg instead
Now to change the permissions. Two ways again.
First way is to right click file and choose properties. Choose permissions tab if on a different one. Click Change Permissions. Then click Add and advanced. Find now and find the name and click OK. Then choose Full Control and click ok to close boxes.
The second way lets you do all files in a folder (or group in it). Do search for cmd in search at Start. Then right click cmd.exe that was found and choose to run as administrator (you need higher rights to do this). Go to folder where files are. Then type in the following command and enter. User name is your name in my example mine is dwight icacls *.* /grant username:F
After doing these steps all her pictures worked again on the PC
Thanks Sophie for the question