I have 2 children a boy 4 1/2 and a girl 2 1/2 feels like I do all I can and am always shouting they nevere listen to a word I say now I feel I am at why witts end...

I think that that is the prcise age that children don't listen... at least lots of them don't... I've worked in a kindergarten before and they don't lsten you are right... but instead of shouting you could try and compromise and I knoe that that sounds crazy but if they don't listen or do anything they say maybe take sómething away from them for a while... or it could also be that something is bothering them or somethinginstead of shouting try other ways like just grabbing them and hugging them... but don't hit them or lock them in their rooms that wiöll just make it worse
And you can try to see it from their point of view and see they way theyd think was OK...
Or ask them why they don't listen to you... although I guess your children are too young for that...
I don't know maybe try this...
How to make your children listen (http://www.essortment.com/all/makechildrenli_rhfj.htm)
I hope this helped you a little... I love children :D
And I know I sound like a freak:P