If, for example, you phoned your friend yesterday and he didn't answer, you could say either 'Were you sleeping?' or 'Were you asleep'? The first is the past continuous form, using the verb 'to be' in the past and the participle with -ing.' The second is using the verb 'to be' in the past and an adjective ('asleep'). The form 'Were you slept' does not exist. You cannot say this.

"We're you asleep?" Works better. Alternatives are: "We're you sleeping," "Dis you just awaken," "did you just wake up?"