Question

1. Paul visited me in order to ask for a help.

2. Paul visited me in order to ask for help.

(Which one is correct? Are both grammatical? What is the difference between them?)

Answer 1

2 is correct; 1 is not. You wouldn't use "a help" in this context because it cannot be counted (is not a "count noun").

http://grammar.ccc.commnet.edu/grammar/noncount.htm