Checkboxes don't appear in my theme

Do you have a link to your project that we could see?

If you are viewing the site in Google Chrome you can right click where you would expect the checkbox to be and click ‘inspect element’ … if you know a little about HTML you can check to see if the checkbox is there in code or if it is not – for example when changing your theme it may well be hiding check boxes via CSS

Do you have a public link to a form in this theme?

this is the website: https://2stalbania.al/alltech/ritiro-hardware-2/
under the form contact I want to add PC,Laptop and Monitor as checkbox

So it looks like your theme is doing some crazy styling on checkboxes, but the way they’ve done it requires a <label> tag. And unfortunately the way it does it requires that the label be after the checkbox, not around it, which is all that Contact Form 7 supports.

You can undo this behaviour by adding this CSS:

[type="checkbox"]:not(:checked),
[type="checkbox"]:checked {
    position: static;
    visibility: visible;
}

You should also inform the theme developer that their theme is not properly compatible with the most popular forms plugin for WordPress.

@jakept you just saved my life ?? It works!! thanks a million .I have been searching it all day.I will inform the theme developer asap.

Thanks again ??