Looking for logging into the Salesforce Admin site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Salesforce Admin site. After that you can login as usual with your login credentials.
https://login.salesforce.com/
https://help.salesforce.com/apex/HTViewSolution%3Furlname%3DEnabling-Organization-Admins-Can-Login-as-Any-User
https://admin.salesforce.com/
https://help.salesforce.com/apex/HTViewHelpDoc%3Fid%3Dlogging_in_as_another_user.htm%26language%3Den
https://success.salesforce.com/answers%3Fid%3D90630000000gwQXAAY
https://trailhead.salesforce.com/credentials/administrator
https://help.salesforce.com/HTViewHelpDoc%3Fid%3Dgranting_login_access.htm
https://help.salesforce.com/apex/HTViewHelpDoc%3Fid%3Dcontrolling_login_access.htm
https://www.webassessor.com/wa.do%3Fpage%3DpublicHome%26branding%3DSALESFORCE
https://www.youtube.com/watch%3Fv%3DRo1Q4jvX6RA
https://salesforce.stackexchange.com/questions/124506/administrator-user-not-able-to-login-to-community
https://webkul.com/blog/grant-login-access-salesforce/
https://www.adminhero.com/lightning-login/