I admit that I'm using a walkthrough and I have got to the palace in baldur's gate and I've killed all of the greater dopplegangers and when they are dead, Sarevok is supposed to attack me they flee, but the problem is he dosen't even attack please assist me through this area!

Did you try talking to him? Also if that doesn't work try attacking him first.

The way it's supposed to work is after you enter the palace talk to Liia and Belt (The other Dukes). This is supposed to cause the Nobles to turn into Dopplegangers and attack you, Serevok should join the assault (I think) you must survive his attack for 10 seconds and then he'll leave. Talk again to Liia and Belt and they should tell you where he went and transport you there. Whatever way you do it, you need to get Serevol out of there and talk to the other Dukes, Note that if the dukes fail to survive that skirmish Falming Fist Mercenaries will spawn into the game until a total of 60 amass onto the screen - Then it's game over, if your computer doesn't crash first.

After I killed 28 of those fist pussies they disappeared.... so as long as your strong enough to whoop 'em they're just pesky insects

When i did thid i entered the room and watched the ceremony and then the dopple gangers
attaked.I killed them with only Belt living and he spoke to me.I showed him sarevoks diary
and then sarevok attacked.After like 10 seconds his mage friend appeared and he and sarevok fled.I spoke to Belt again and he teleported me to where sarevok went.
What you have sounds like a bug.