Downloaded materials can't load texture

I had a problem where the texture of a material would change to the default black and grey box pattern whenever clicked. I’ve come to find out that the problem is the material can’t load it’s texture. When I create a local material from the texture it works fine. Is this a problem with my system or the files cause other people who downloaded the same files aren’t having this problem. Is there a way to rebuild the materials with the right texture?