There may be several reasons.

1. The email address or password you entered is incorrect.

2. The first time you log in to Facebook, you need to click the "Sign in with Facebook" button to log in.

3. If you still cannot log in, you can reset your password. Click "Sign in" in the upper right corner of the homepage, then select "Forgot Your Password", enter your registered email address in the box provided, you can receive the reset email, and create a new password with the link.

If you can't find our email, please check your spam folder.