How to fix?

[sahagunethan]

[ClockworkOcean]

Your UV map is not right, what did you do to get this? ( I think maybe you're putting a different material on a mesh, than was intended? )

[KhappaMJ]

If your model comes from a 3D software such as 3DsMax for example, you have to adapt the UV coordinates on it, otherwise try to unlink the texture tiling coordinates in the material editor and re-connect it