I was trying to enable Lightning on my salesforce account , and as I read from your trailhead website, that I should change "my Domain", but when I did that, it display this message for everything in my account : "An error has occurred in the following section: [Exception, DomainNotPropagated]. Salesforce.com has been notified of this error." and now I can't do any thing on the website and I can't solve it.
so what is the problem and how could I solve it.

I tried to contact support, but I couldn't even reach to contact page to open a case
please help

I was trying to enable Lightning on my salesforce account , and as I read from your trailhead website, that I should change "my Domain", but when I did that, it display this message for everything in my account : "An error has occurred in the following section: [Exception, DomainNotPropagated]. Salesforce.com has been notified of this error." and now I can't do any thing on the website and I can't solve it.
so what is the problem and how could I solve it.

I tried to contact support, but I couldn't even reach to contact page to open a case
please help