html input only letters
snippet in html

html textbox pattern mobile number

user1940

<input type="text" name="Phone Number" pattern="[7-9]{1}[0-9]{9}" 
       title="Phone number with 7-9 and remaing 9 digit with 0-9">

name validation html

user7152


<input type="text" pattern="[a-zA-Z'-'\s]*">

html input only letters

user9474

<!--To stop input from accepting numbers-->
<input onkeypress="return /[a-z]/i.test(event.key)" >