Briggs law firm Demanding a Personel loan payed back. threating me with forslosure ect. No information given as to where or when loan was taken out. The proff or photo of documents that are to be include are blank. no information given where this is from Internet

I have been contacted by a Law firm stating I took out a personal loan and did not pay it back . Attached to the e-mail is supposed to be proof of my taking out the loan, but the pictures will not open.  have been treatened that i will loose everything if I do not pay this back. The information i request as to where and when loan was taken out, they refer me to the pictures inclosed that can't be seen .I have tried to get information on this company over the internet, not sure if it's a legal company or not.  Any help or suggestions?