404 issue can happen because of two reasons.
You should first make sure your hosting provider has installed/enabled
mod_rewrite. if mod_rewrite is already installed and enabled you should then
make sure you have uploaded your .htaccess if your in Mac you cannot see the
.htaccess. Please read below post if your using a Mac.
Also you can try adding below code to you .htaccess right after the code
RewriteBase / RewriteRule ^index\.html?$ / [NC,R,L]
If all above fails please contact us using our contact form.