Help kids wont listen!!

It sounds like they need to see you in control. They need quiet answers, hugs and consistency. Get creative and keep them busy. Also watch Nanny 911 reruns to get ideas and strengthen yourself. These are difficult years, things will change. When you feel like "loosing it" try asking for hugs ! It will benefit all of you. Hang in there. We can all relate. Speak quietly, walk away and don't give them attention when they are trying to "push your buttons". You can also start a reward system for your 4 yr old. Get a calendar or chart and give them easy behavior expectations and tasks to earn sticker for the day. You can tie in trips to McDonalds and special things to reward the positive behavior. You don't have to argue- if they earn it- great and if they start to misbehave they can lose it.

You need to have a melt down in front of them. Go into the living room sit down on the floor and start screaming your head off. (Just don't lose your voice.) They will come to you to see what is going on or they might get scared and start crying because they want you to stop. Now that you have their attention, sit down with them and explain that this is what they do to you and you don't like it. Tell them that if their behavior changes you will reward them with something. (You can decide on the reward.) They will eventually learn that screaming isn't going to get them anywhere.

If your daughter is tattling about something that happened to or upset her, respond in a way that gives her guidance about how to resolve conflicts or handle disputes. Start by consulting her for her own reaction/assessment. Ask, "Did you like that?" When she says "No," guide her through what to do. Accompany her & follow through. It's a matter of telling her how to speak for herself & how to communicate in times of conflict. If she tattles that her brother grabbed her marker or hit her, ask her if she liked it, then tell her, "Tell your brother, 'Stop! I don't like that. If you want to draw, ask me where the markers are.'" This conveys understanding for WHY he was grabby/aggressive in the first place, which builds her empathy for him, but honors her limits. This of course can apply to other complaints, and to conflicts you intervene in (when they're just hitting/biting each other.) Assume positive intent, provide guidance.

If they call you names when upset, consider acknowledging their upset. "Reflect" what they say back to them in a way that models a more mature way of expressing the same exact feeling. (Feelings don't go away. You can't make it so they DON'T get upset when things don't go their way! What you can do is guide them by accepting their feelings, rather than struggling against them, while modeling more appropriate expressiveness.)
If they're upset about something & say "You dummy!" or "Poo-poo head" or whatever form of name-calling they resort to, look at them & acknowledge what you know about what happened. "Yes, you didn't want Mommy to take that away," or "You didn't LIKE when I said no!" or "You wanted to do it yourself!" Reflect the emotional content, rather than attributing "disrespect" to their impulsive outburst. You're showing understanding/acceptance for feelings AND providing guidance for how to express their upsets.

The way you respond to "fits" matters. I don't "ignore" kids who are having tantrums because I think the emotional leverage ("you can only have my attention/approval if you please me") has serious negative consequences, neurologically & emotionally. It is essentially as coercive as getting angry in hopes of intimidating them out of the behavior.
But it's important not to "reward" the tantrums, either. This means, you need to be able to stay regulated yourself so that you don't desperately "need" the crying to stop. How you see the crying can make a difference. When I focus on acknowledging what happened leading up to the upset, I can hear a child's crying/screaming as an expression of her frustration & as her attempts to come to terms with a limit & regain her emotional balance. It's a grieving process. I don't have to fight against it or "make her stop," AND I don't have to feel like something needs to happen or be changed.

Same with your 2 year old son. Take responsibility for yourself & for him, and hold him so he can't "beat you up." Be proactive & contain him so he can't lash out (while staying warm & understanding of his frustration, ideally) or else disengage his "assault" as soon as you can, and contain him. Don't let him get so physically out of control that he hurts you with his kicking or hitting, or his hair-pulling, pinching or biting. Let him know that you can't let anyone get hurt, and that you're holding him so everybody's safe. Keep acknowledging his frustration and how it all makes sense (that he was upset in the first place, and that having to struggle & be restrained is very upsetting, too.)
We parents have to protect ourselves, which helps us stay responsible for our feelings (by protecting us from feeling anger/retaliation when we're physically hurt.) Kids depend on this. We keep them safe in this way.

And when he's having a fit (but not attacking you/someone else), it's like any tantrum. It's not your "job" to stop them when they happen, or to somehow force him not to express those feelings. He's processing fury & grief.
At those times (which ideally will become fewer, the more responsive you are to him), he is overwhelmed. Provide acknowledgment. If you know what happened, acknowledge that. "You didn't want Mommy to take that away." "You wanted to have the scissors!" "You didn't WANT to turn off the TV!" "You didn't want to be scooted closer." You cut his sandwich "wrong" or whatever. If you're not sure, you can acknowledge that "Something happened" & show that his feelings make sense. You see how he's really upset. Things aren't going his way.
Don't try to explain why you "had" to do something, or reason with him. Just give acknowledgment.
This way, he can stop struggling for the RIGHT to his feelings, as he's been doing.