Is it possible to load the data of registered customer to my form?

Is it possible to register visitor through jot form and if visitor will come back after registering he doesn't have to fill name email and phone no.?

He will have his username and password basically

Unfortunately, you cannot use our form as a way to have a Login page or login form.

Every time you use elements on the form that resembles it as login page or form (i.e. login name, password, email account/password combo, account name/password combo, username/password ) the Anti-Phishing system in place will immediately suspect it as a phishing form, and will suspend the form/s and the account.

However, you can achieve that by using Spreadsheet to form widget, this will get the data from google spreadsheet to your form, but the user needs to know his/her unique code to load the data from your spreadsheet. (Though I'm not sure if you can load specific data only like "email,number", I suggest to try it on the cloned version of your form)

You can check this guide for more details: How to Use the Spreadsheet to Form Widget.

By the way, you need to integrate your form to spreadsheet first so that your submissions data will go to the spreadsheet.

Here's a guide: How to Integrate Forms with Google Sheets.