What program to read .rez file or editing it?

I tried using notepad but I cannot read the characters, I deleted some of them hoping that will make some changes. But turn out, I cant shoot my SMG or do anything about it. Btw, need some help with the .rez file weapon backup.
Can u plz help me?

Erm, why did you do that. you cannot read REZ files only decompress them to see the LTB files.