Forbidden: You don't have permission to access this resource

[jsb_15]

I am new to all this. I have a PHP file that has HTML in it. When running it on localhost, the HTML comes up, but when I enter a number in an input "text" it gives me the above message. I have read some of the responses to a similar question, but I find them confusing. I have checked permissions for the Apache directory as well as for htdocs. I am the only user of my computer and I have read/write permissions for the Xampp directory, the Apache directory and the htdocs directory. I checked those by right clicking on the directories in the Windows file directory. I am at a loss as what to try next.

[Nobbie]

Show us the source code please.