In the State of WA, I am my fathers only child. Had no wife and no will at the time of passing. Estate will be in foreclosure soon, my family has already packed and moved a lot of the house (not knowing what was all his?). Is the estate and all my fathers belongings my responsibility being I the only next of kin? If so what are the steps I should take to get his belonging back and estate closer in proses? '.

In WA if you are the only child of the deceased (he never had any other children), then his estate passes 100% to his "issue," which means you. You need to have yourself appointed as the estate's Personal Representative (also called "executor" in some states), so that you have authority to use his assets to pay off any outstanding debts and ultimately transfer assets to the heir (you). You apply to the court for a "grant of probate" see: Executor of Estate