This example does sound wrong to a native English speaker.
It contains a subjunctive mood construct and the correct version would be:
"What if there were no stars in the sky?"
"What if there were no stars in the sky?"
Note that not all native speakers of English use or prefer this type of construction. Also, this use of "were" instead of "was" is sometimes now called irrealis and considered separate from the subjunctive (which is then used to refer only to constructions like "it's important that you be here early tomorrow").
At the end of the day there is accepted grammar and there is actual usage.
If you ask people for the accepted grammar they will give you something most people accept. Which is not "What if there were no star in the sky?"