Steps to reset security token in Salesforce

1. Login to Salesforce with your account
2. Select Setup
3. Select My Personal Information
4. Select Reset My Security Token
5. Click the button Reset Security Token
6. An e-mail will be sent to your account with the token, get this token and use it in your application

If the security token is not correct, your application may show an error like that: {"INVALID_LOGIN: Invalid username, password, security token; or user locked out."}