Q:

Synonym for "he's senseless"

He's senseless since yesterday. 

Can I say the quoted sentence as 

His sense didn't (return/come back)(i) since yesterday 

–if not, what will be appropriate at position (i)? 

A:

It would be better to say His senses (meaning sight, hearing etc.) have not come back. Sense in the singular would be taken to mean common sense. 
However, the most idiomatic version would be He has been unconscious since yesterday.

