Issue:

My HTML form is working except the file upload.

How to solve:

1. A consideration to make when uploading a file is that your HTML form must contain the ENCTYPE attribute in the <FORM> tag:

<form method="post" action="form.php" enctype="multipart/form-data">

2. The file size is bigger than the size limited by the webhosting provider. Ask your webhosting provider.

3. The server configuration doesn't permits file uploads for security reasons. Ask your webhosting provider.