i dont have my credintials like password so what i do

Hi Gayatri,

If you mean your Trailhead Playground password, you don't need to know the password you originally created. You can reset it from the Playground:

1. Go to Trailhead → your profile → Hands-on Orgs.
2. Find your Playground and click Open.
3. In the Playground, go to Setup → Users → Users.
4. Find your user and click Reset Password.

Salesforce will send a password reset email to the email address associated with your Playground user.

If you're referring to your Trailhead account password instead, use the Forgot Password option on the Salesforce login page.