Thanks for the reply but there is no problem with the spelling as it's been double checked.
I'm told that to fix the problem, I am going to need that htaccess file
No. You don't need the htaccess file.
As explained, you need to correct your spelling.
On your page, you have spelled the file name next.jpg. Sensible to use only lower case letters for file names. However, the filename isn't next.jpg, it is Next.jpg.
If we spell it correctly, we can display the button without any htaccess nonsense:
Since using lowercase letters is wise, I suggest you change the filename to match the code. Also, of course, there is only one filename to change, and several pages with coding that does not match, so it will be quicker to change the file name.
As far as I can tell, everything is working, except possibly for cached files in your temporary internet files. But if you can tell us about something that doesn't appear to be working, we can check.
PS:
How long have you had that site? There are still "no-right-click" scripts on some of the pages. Cute. Reminds me of the nineties, when people still thought of those as "protection".