Be in the way; undermine; counteract.
The opposite of help is hinder.
Hurt is the opposite of help.
The opposite of hinder is to help, aid, or assist.
unhelpful, helpless
Not sure that HELP has a proper opposite, Don't help, No help, hope someone else can offer you a better answer.It's harm
the opposite of unpleasant is gratefully please send for more help
The opposite could be help, also love, care, or nurture.
Aid, help
No. It does the opposite.
harm hurt
The opposite of prevent is cause.Aid, allow, assist, help, let go, cause...
An antonym would be, "I was uncertain/unsure to ask help on the assignment." Both words are the opposite of certain.