we are using ldap authentication to get user, ldap password was reset now we are not able to logina

It is a best practice to exclude at least one admin account from the LDAP authentication. If you followed it, that should not be an issue. If you did not, and this is a cloud environment, I suggest to open a support ticket and see whether Appian support can help you.

Try with this plugin for sync user's profile (but without admin user, probably you won't be able to install it)

community.appian.com/.../ldap-tools

You need to raise the support case with the Appian. The Appian support team will run some scripts to reset the Administrator account. It is only applicable to the Administrator account in the Appian.