What can be done to get back a property that was sold at a sheriff’s sale?

This inquiry referenced to my deceased spouse's property that a company called CoreStates Group purchased at sheriff’s sale due to my spouse's delinquent tax debt. The property was the family home left to my spouse by his mother after her passing. Her wish was that the home be passed to his children and was adamant about it staying in the family. My spouse passed away November 27, 2014. My children and I reside in another state and were not aware the property was in such a state. My spouse’s sister whose name was included as executer of the property was never contacted about the property being up for sale by the sheriff’s office. Unfortunately, the sister passed away a few months ago but her husband was as shocked as we were because he said they never received a notice as to the sale. I reached out to The Office of Property Assessment who referred me to the Recorder of Deeds who referred me to the Sheriff’s office who referred me to CoreStates Group who referred me to their lawyer and somewhere along the line I lost track. At some point, I was told to have some type of writ filed. Please advise as to whether anything could be done about the situation.