Let me take this question from the beginning of the problem.

When you enter a web address into a browser that browser downloads the code onto your computer and analyses it for mistakes. If there is no definition for the document then the browser has to try and work out what format it is. If the code has errors the browser will try to work out what the programmer wanted to happen and display that.

In real time this all happens in seconds. With too many mistakes a website does not display as intended and in worst cases does not display at all.

For people with disabilities the text or images on your website may be totally inaccessible if they rely on table formats for positioning or if there are not alternative descriptions available for text content. Blind people need to use braille readers to convert the website to their format of choice or they may decide to use an audio content reader to audibly speak the contents of the website out loud. Large print books are common in libraries and there are techniques by which people can have the same effect on websites in their own browser, if the site that they are downloading is correctly programmed.