You need to use the same social account again, which you have used to authentication before

{ "email": "test123@gmail.com", "password": "123" } I have email and password how can I login and match user email and password

there is no password login, you need to use oauth login with your provider at https://gorest.co.in/consumer/login

currently google, github, microsoft/outlook are supported. Just click on the respective provider link/icon