Can't login, password reset link loads blank page, cookies blocked

I am trying to login to a site that I have not logged into for a year or so and don’t know which version it is.

I get the following message:

ERROR: Cookies are blocked or not supported by your browser. You must enable cookies to use WordPress.

After googling I find posts like this that suggest to comment out code in wp-login but didn’t work.

How could I troubleshoot this? I do have cpanel access.