When should the phrase '괜찮아요' be used? Are there any alternatives?

Question

Answer

괜찮아요 means.. "it's ok."
Not so good.. but it's ok.. 

for example
when you fell down. or your heart is broken.or someone step on you. etc... 
someone ask.. "are you alright?"
then you'll say '괜찮아요' 

 or other case
. you go to some shopping with your friend.. .. your friend  will ask you about the stuff .. 
"what do you think about it?"
 then you can say.." 괜찮아!".. (that's not bad..")

 ..Alternative .. hmm....
 I'm not sure about it.. ha ha sorry.. ^^

Answer

괜찮아요 - it is ok
뭘요, 아무것도 아니에요, 별말씀을요 - it is nothing
상관없어요 - im ok whatever
문제 없어요 - no problem

Answer

1. usage
SEE       http://www.koreanwikiproject.com/wiki/index.php?title=%EC%95%84/%EC%96%B4_%2B_%EB%8F%84_%EA%B4%9C%EC%B0%AE%EB%8B%A4

2. alternatives
좋아요, 상관없어요 or 문제없어요 depending on the situation