Icons preview problem

Guys, i used to change icons easily , but recently i'm unable to change the icons , fairly few of them can be changed.
When i "get info" of any folder or picture the icon is not displayed it just shows as the preview icon of the default viewer , see attached screen shot
actually this happens to most of the icons , but the existing ones preview is normal

Please help !!

View attachment Picture 1.pdf

Try changing the file extension from .gif to .png when saving to desktop or what ever destination you choose when saving. If you are using command "c" and command "v" method this can become trying if the file has the wrong extension. Also may I suggest candy bar? You can drag and drop images of your choice into the app, then drag and drop over the icon you want to change and when you want to remove just drag and drop off of app icon. This is a quick and easy method. Best of luck.

well the problem is , whatever extension of picture is added it still don't preview the icons when i "get info".
It used to be normal before and i really have no idea what happened.
Also i tried repairing permissions but no joy , any ideas??