Hi Saimanti Das,
From your description, there should be a couple of options available.
1. Depending on the type of authorization being used in your instance, you might see the following "password reset" option available when logging into your instance:
2. If you are authenticating through an external identity management system (LDAP/SAML) you might have alternative options available, so would suggest reaching out to the Community Manager of your instance as they might have a more targeted reply for your specific configuration.
3. An admin of your instance might also have the following option available to them via the admin console >> people page as well:
Thank you very much. AD worked.