Hi,

Please test if the success information is shown when clicking the submit button of the contact form.

If it is not shown, there may be some script issues. Please stop all 3rd plugins to check again. If it still doesn’t work, please leave the contact form page URL.

If it is shown, it mostly is cased the 2 reasons:

1) Check the mailbox that set for receiving the form, It may be moved to the spam box automatically.

2) There is some issue in your mail server, the mail server is forbidden by some host suppliers. Please contact your host supplier.
OR set your own SMTP sender:
please install this plugin: https://wordpress.org/plugins/wp-mail-smtp/
refer to how to set: https://wpforms.com/how-to-securely-send-wordpress-emails-using-gmail-smtp/