"If there were" vs. "if there was" [closed]
Solution 1:
"Were" would be subjunctive, expressing a condition contrary to fact ("If there were anything that he didn't want [but there wasn't anything that he didn't want]"); "was" would be a simple condition. So you want "was" here.
Solution 2:
Slightly off-topic, but I think it's the "anything" that makes the sentence a little awkward. Maybe "one thing" would be better.