Who should I ask for my money??

[Di Chen]

hello every one, I'm a newbie investor and I just closed the escrow on a house last month, now I'm in headache because I just found out the a/c unit needs to be replaced and the escrow is closed. What happened was that the inspector stated there was no power for the ac when he was there, therefore my agent didn't include the ac fix in the repair list, after the escrow closed and I've handed my house over to the management company they came back to me telling me the ac is broken, needs to be replaced, as well as the fireplace, the gas pipes are all busted as if it got burned completely before. Here are some facts about the transaction: the seller didn't disclose anything that wasn't working, my agent didn't include the ac in the repair list( on the inspection report it says the power source for forced air does not operate, the cooling system was not operated) and I don't know why. We didn't buy home warranty, seller never offered nor did my agent. 

I really wish somebody could help me out here, really appreciated!

Di