Bunkless Bovian took the witness stand in Brooklyn Supreme Court yesterday to testify against deli clerk Salah Ahmed, who's on trial for hitting him on the head with a hammer during a brawl in his East New York store last April. Bovian (pictured), 16, told the jury he doesn't remember the details leading up to the incident, and only recalls "waking up in the hospital thinking I got stabbed... I still get bad headaches. Sometimes, I can't even lift my head off my pillow." But the attorney defending Ahmed pounced on the teen's testimony, asking, "You don't remember jumping on the counter and stomping on the clerk? Your memory seems to be a little selective. Do you remember anything bad you've done?"Bovian said he does recall being on friendly terms with Ahmed at one time, even helping him carry in sodas. But now the ninth grader thinks "he should go to jail. My dream was to go to the NBA... I used to get 30 points a game. Now, they hardly let me play." If convicted, Ahmed faces up to 25 years in prison.