You are supposed to be served with a "Notice of Mortgage Foreclosure Sale" at least four weeks before the sale is scheduled to occur. The process server is supposed to try to serve you personally ... and if they try to server you with the paperwork at least twice, with one of those instances between 6:00pm and 10:00pm then the process server can leave a copy of the notice at the door. You can contact the sheriff's office and ask if there is a sheriff's sale scheduled if you really think one has been scheduled. If you want to discuss what some of your options are then just give me a call or shoot me an email. I offer a free consultation.
Very best regards,
Errin P. Stowell
Stowell Law Firm, LLC
350 St. Peter Street, Suite 224
St. Paul, MN 55108
Also, if you have had a previous foreclosure sale scheduled, and you received service related to the previous one, the foreclosing party may merely send you notice of the new foreclosure date. That is, service is not required under Minn. Stat. 580 to postpone. To find the date of the sheriff's sale, you can either look to the publication of the foreclosure or go to the County Recorder to get the Notice of Pendency of Foreclosure Sale.
If you have not been properly served, that may be a basis to cancel the sheriff's sale. But the likelihood of that is dependent also on what the affidavit of service says, which you won't know until after the sheriff's sale.
Overall, you should consult an attorney.