Narrowing down the possibilities...
1. Browser set to text only. This can be done deliberately, or in the vast sea of computer users, it could be the result of a disk error, software bug, memory chip glitch, virus, defective installation program, etc.
2. ISP glitch. Images are mostly in the form of .jpgs ane .gifs. They are not "in" the page; they are requested by the browser as the page loads. Perhaps an ISP temporarily blocks images to cope with a performance problem, or perhaps they have one of the problems in point one.