Recently I asked the theme developer to add a payment gateway logo in my footer and create an external link for the social icon in footer, although it worked really well but due to some error, many other things in the website got disturbed.
1- Cant see the related product section on the product page
2- Add to cart button isn’t working
3- Can’t access header menu on mobile
4- Header Slide show on the home page isn’t working
5- If you open the search box on the home page you won’t be able to close it then
While we’re not able to provide support for custom coding performed by an outside developer, there are still a couple of things we can recommend here for your next steps.
The first would be to contact the developer you used for these tasks to let them know there may have been unintended consequences to their work.
If they are unable or unwilling to provide this support, you may be able to undo these issues by rolling back to an older version of your theme.