checked on the internet, here is what I got

Singular is use in following situation:

"Any question can be answered..."
"Any child can learn to swim"
"Any wall can be torn down" etc

Plural is used in following situation

If you explain something at a conference (for example), in the end you would say "Any questions?".

for detailed discussion please see

http://english.stackexchange.com/questions/23618/should-i-write-any-question-or-any-questions